All IC2 crafting recipes (besides jetpack attaching and Q-suit dyeing) and most machine recipes are loaded from ini files within the IC2 jar. These can be copied to a (new) ic2 folder in the config folder and any changes made to them there will be reflected in game. This provides more direct access to change the recipes as desired, compared to CraftTweaker which effectively hacks over them after they've already been added. Whilst the format isn't the same as CraftTweaker, it is well explained at the top of each file, as well as there being the examples of all the pre-existing recipes.
