To become a Viltrumite you will have to put on the 'Pure Smart-Atom's Injector'.
In order to gain levels as a Viltrumite, you will have to take massive damage for each instance. The higher the damage, the more experience you gain. Or, alternatively, simply do physical training such as running, jumping, and punching mobs.
If you don't know how to install Lucraft addons, please watch and finish this video.
https://www.youtube.com/watch?v=d36qSLCkmXI
All the dependencies required.
https://www.curseforge.com/minecraft/mc-mods/lucraft-core
https://www.curseforge.com/minecraft/mc-mods/electroblobs-wizardry
https://www.curseforge.com/minecraft/mc-mods/the-fifth-world
https://www.curseforge.com/minecraft/mc-mods/tickratechanger
Recommended mods(also half depencies).
https://www.curseforge.com/minecraft/mc-mods/speedster-heroes
https://www.curseforge.com/minecraft/mc-mods/heroesexpansion
https://www.curseforge.com/minecraft/mc-mods/attributefix
https://www.curseforge.com/minecraft/mc-mods/classic-bars
FOR BEST EXPERIENCE USE JEI (JUST ENOUGH ITEMS) MOD!!!!!!