I loaded Inventory Tweaks fine before I put my custom configuration file into the .jar. I'll provide both the crash report and the config file.

The crash report:

---- Minecraft Crash Report ----
// Ooh. Shiny.

Time: 5/21/14 6:22 PM
Description: There was a severe problem during mod loading that has caused the game to fail

cpw.mods.fml.common.LoaderException: java.lang.IllegalAccessError: tried to access field net.minecraft.client.settings.KeyBinding.field_74512_d from class invtweaks.InvTweaksObfuscation
at cpw.mods.fml.common.LoadController.transition(LoadController.java:162)
at cpw.mods.fml.common.Loader.initializeMods(Loader.java:688)
at cpw.mods.fml.client.FMLClientHandler.finishMinecraftLoading(FMLClientHandler.java:288)
at net.minecraft.client.Minecraft.func_71384_a(Minecraft.java:527)
at net.minecraft.client.Minecraft.func_99999_d(Minecraft.java:815)
at net.minecraft.client.main.Main.main(SourceFile:103)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.minecraft.launchwrapper.Launch.launch(Launch.java:134)
at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
Caused by: java.lang.IllegalAccessError: tried to access field net.minecraft.client.settings.KeyBinding.field_74512_d from class invtweaks.InvTweaksObfuscation
at invtweaks.InvTweaksObfuscation.getKeyBindingForwardKeyCode(InvTweaksObfuscation.java:102)
at invtweaks.InvTweaksHandlerShortcuts.loadShortcuts(InvTweaksHandlerShortcuts.java:76)
at invtweaks.InvTweaksConfigManager.loadConfig(InvTweaksConfigManager.java:144)
at invtweaks.InvTweaksConfigManager.makeSureConfigurationIsLoaded(InvTweaksConfigManager.java:59)
at invtweaks.InvTweaks.(InvTweaks.java:105)
at invtweaks.forge.ClientProxy.init(ClientProxy.java:40)
at invtweaks.forge.InvTweaksMod.init(InvTweaksMod.java:37)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:513)
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:208)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:187)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:47)
at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
at com.google.common.eventbus.EventBus.post(EventBus.java:267)
at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
at cpw.mods.fml.common.Loader.initializeMods(Loader.java:687)
... 10 more

A detailed walkthrough of the error, its code path and all known details is as follows:

-- System Details --
Details:
Minecraft Version: 1.7.2
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.7.0_51, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 217191376 bytes (207 MB) / 490209280 bytes (467 MB) up to 954728448 bytes (910 MB)
JVM Flags: 2 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G
AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP v9.03 FML v7.2.196.1084 Minecraft Forge 10.12.1.1084 Optifine OptiFine_1.7.2_HD_U_C2 26 mods loaded, 26 mods active
mcp{9.03} Minecraft Coder Pack Unloaded->Constructed->Pre-initialized->Initialized
FML{7.2.196.1084} Forge Mod Loader Unloaded->Constructed->Pre-initialized->Initialized
Forge{10.12.1.1084} Minecraft Forge Unloaded->Constructed->Pre-initialized->Initialized
CodeChickenCore{1.0.0} CodeChicken Core Unloaded->Constructed->Pre-initialized->Initialized
NotEnoughItems{1.0.1} Not Enough Items Unloaded->Constructed->Pre-initialized->Initialized
OpenEye{0.5} OpenEye Unloaded->Constructed->Pre-initialized->Initialized
bspkrsCore{6.8(1.7.2)} bspkrsCore Unloaded->Constructed->Pre-initialized->Initialized
DamageIndicatorsMod{3.0.8} Damage Indicators Unloaded->Constructed->Pre-initialized->Initialized
DirectionHUD{1.21(1.7.2)} DirectionHUD Unloaded->Constructed->Pre-initialized->Initialized
FloatingRuins{1.7.2.r04} FloatingRuins Unloaded->Constructed->Pre-initialized->Initialized
WorldStateCheckpoints{1.7.2.r02} WorldStateCheckpoints Unloaded->Constructed->Pre-initialized->Initialized
AnimationAPI{1.2.1} AnimationAPI Unloaded->Constructed->Pre-initialized->Initialized
Backpack{2.0.0-pre1} Backpack Unloaded->Constructed->Pre-initialized->Initialized
BiblioCraft{1.7.0} BiblioCraft Unloaded->Constructed->Pre-initialized->Initialized
Mantle{1.7.2-132.45b0b50} Mantle Unloaded->Constructed->Pre-initialized->Initialized
Natura{2.2.0} Natura Unloaded->Constructed->Pre-initialized->Initialized
BiomesOPlenty{2.0.0} Biomes O' Plenty Unloaded->Constructed->Pre-initialized->Initialized
DragonMounts{r38} Dragon Mounts Unloaded->Constructed->Pre-initialized->Initialized
HardcoreEnderExpansion{1.6} Hardcore Ender Expansion Unloaded->Constructed->Pre-initialized->Initialized
inventorytweaks{1.58-dev-123} Inventory Tweaks Unloaded->Constructed->Pre-initialized->Errored
MapWriter{2.1.1} MapWriter Unloaded->Constructed->Pre-initialized->Initialized
meteors{2.12} Falling Meteors Unloaded->Constructed->Pre-initialized->Initialized
MutantCreatures{1.4.5} Mutant Creatures Unloaded->Constructed->Pre-initialized->Initialized
Mystcraft{@Version@} Mystcraft Unloaded->Constructed->Pre-initialized->Initialized
Roguelike{1.3.0} Roguelike Dungeons Unloaded->Constructed->Pre-initialized->Initialized
TwilightForest{2.0.3} The Twilight Forest Unloaded->Constructed->Pre-initialized->Initialized

And the config.:

SpecialSource needs to update to handle these.
public net.minecraft.client.gui.inventory.GuiContainerCreative$ContainerCreative
public net.minecraft.client.gui.inventory.GuiContainerCreative$CreativeSlot
public net.minecraft.client.gui.inventory.GuiContainerCreative$CreativeSlot field_148332_b # theSlot
public net.minecraft.client.settings.KeyBinding field_74512_d # keyCode
public net.minecraft.client.gui.inventory.GuiContainer field_147003_i # guiLeft (1.6 field_74198_m)
public net.minecraft.client.gui.inventory.GuiContainer field_147009_r # guiTop (1.6 field_74197_n)
public net.minecraft.client.gui.inventory.GuiContainer field_146999_f # xSize (1.6 field_74194_b)
public net.minecraft.client.gui.inventory.GuiContainer field_147000_g # ySize (1.6 field_74195_c)
public net.minecraft.client.gui.GuiScreen field_146292_n # buttonList (1.6 field_73887_h)

====== [ SETTINGS ] ======

A3-A8 naturalBlocks
B1-B9 naturalBlocks
A9 edibleFood
B9 edibleFood
C9 edibleFood
A1-A2 Arrows
D1 Sword
D2 Bow
D3 Pickaxe
D4 Shovel
D5
D6
D7
D8 Torch
D9 edibleFood
C1 Sword
C2 Pickaxe
C3 Shovel
C4 Axe

That's more of 'you installed the mod incorrectly' (or some other coremod is decided to overwrite the access changes somehow, probably be being stupid)

My bad, I was just putting the configuration in the wrong place. Sorry to bother you.