Cannot find any way to add Syngas produced via Advanced Generators mod as a fuel available for the Combustion Generator. It pumps through fluid pipes from EIO just fine though. It's just that the generator doesn't know what to do with it.

It is basically carbon atomized into steam to create a fuel that is better than simple coal. The main point here is to allow the EIO combustion generator to stand in as an stand in between building the syngas producer and a gas turbine generator, since they are multi-blocks and take a fair amount of resources.

EIO uses buildcraft fuel registry, from what I've heard.
If your mod adds the fuel registration, EIO would pick it up, I presume.

You can add fuels via IMC. See: https://github.com/SleepyTrousers/EnderIO/blob/1.9/src/main/java/crazypants/enderio/api/IMC.java#L106

This effectively calls this method with the IMC NBT data:
https://github.com/SleepyTrousers/EnderIO/blob/1.9/src/main/java/crazypants/enderio/fluid/FluidFuelRegister.java#L92

Note, you dont need the API for this and shouldnt use it. Just copy the value of the constants then you have no dep on EIO code at all.
If you need any help just ask on the EIO IRC channel

FYI, EIO does use the contents of the BC fluid registry as well, so registering the fuel in BC will also reg. it in EIO. I am pretty sure it doesnt work the other way around though

Oh, I'm just an end-user of the mod. It isn't mine. I was just hoping there was a config option in EIO to add the fuel... guess I'll share this post with the mod author.