If it didnt sit flush, you shouldnt have broken it. You need to put the car into gear and rock it a few times so the gear inside the tranny turns, allowing the gear on your speed sensor to slide down into it. It helps if you have a friend so you can try to jam it in while hes rocking the car, instead of rocking it, trying, rocking again, trying again, etc.I think you need that "top black peice" so that once you get it into the tranny it will actually stay there, i think the black peice has a clip inside of it so it will lock onto the top of the transmission. Otherwise it will pop out from the force of the gears spinning together.
Oh and also i dont think you can use the integra speed sensor, but i might be wrong. I think you need one from a D series (the one from the 95 dx should work fine).
if anybody has info please let me know! help a honda duu out