AFAIK most 60 FPS codes simply adjust the internal timing of the game. If the game is running in 60 Hz mode but only gets 30 FPS, the timing is probably dividing by 2 somewhere to halve 60 into 30. If you change the timing to 1 instead of 2, the game will generate every frame instead of every other frame, which boosts you from 30 -> 60.
*waits for somebody to stroll in to debunk this*
*waits for somebody to stroll in to debunk this*