how do you do a hydro conversion?

I was just wondering what was involved in making a hydro conversion? Do you just change out the transmission to like a B16A2 trany or a B18c trany and thats it, or is it more than that?

if your talking about your car, then its already a hydro. but converting cable to hydro is hard because first you need all the hydro stuff, like all the hydraulic lines, clutch master cylinder thingy. idk what else. i think it would be easier just to go buy a cable tranny