You'll definitely want to implement IReactorComponent, for a simple fuel rod I guess you would just follow the same logic that ItemReactorUranium does to implement all the methods. Some of the IReactorComponent methods aren't typically needed for a fuel rod so looking in Uranium's super class shows you what the defaults should be to avoid unintentionally interfering with the reactor (which leaving Eclipse's auto-generated returns could do). The logic won't transpose perfectly as Item (which you'll want to be extending too) doesn't have all the methods Uranium needs in terms of damage storage especially, but fundamentally you're just storing the value in the ItemStack's NBT and don't need all the extra logic IC2 has for flexibility so the amount of implementing for that you need to do is reasonably limited.
Doing a completely custom fuel rod implementation is all about doing the heat producing logic in processChamber and doing power production either in acceptUraniumPulse or also in processChamber, depending on how you want your fuel rod to work. A reactor only ticks once a second (rather than the normal game's 20 times), so things at slowed down more comparatively to make live debugging a little easier without needing break points.