This was written to me by fast1.8sohcDSM. I had the same question and this is what he said:
To answer your 4G63T question, that is simple. ITS HARD AS HELL,

! THe transmission, for one, yeah its the same size, the fork is the same size too, but lets put it this way, you have a 5 BOLT flywheel, and it's defintely smaller, and you also have a small clutch set. SO that would all have to to replaced. Now if I were you, and I am not, I would make sure I have some good experience under my belt before I start thinking of doing a conversion. YOUR WIRING HARNESS IS TOTALLY DIFFERENT, your missing your coil pack wires, and the Cam/crank shaft positioner. Not to mention knock sensors and all that crap. So basically you would have to put a new wiring harness in from a turbo 1st gen, buy a turbo'd ECM, if it didn't come with injectors, you would have to get them. ANything it didn't come with you would get. THe only compatable thing you would have is your air filter. LoL, I know that sounds rediculous, but its the truth. A conversion of this mulitude, would cost... I would say around 2.5K.