Nevermind this, I saw a thing called Firespitter.
I know the engine and engine fx modules already exist but what do I put in my plugin code to make a part produce thrust? I'm trying to figure out how the stock engine module works but I'm having issues with that because I can't see the source for it. I at least know it increments/decrements a vector based on throttle and fuel input somehow and the api documentation at the wiki isn't showing the somehow.