Well I just did it. I can't say for sure that it would be impossible to do it on the car, and if someone offered me a million dollars I would give it a try, but it might not be possible. And even if you could it would be a lot harder than just taking the alternator off, which was very easy to do. The whole job took me 1 hr 15 min, and I took my time. The problem with doing it on the car is there is a plastic cover on the back that has to come off. It is held with 3 screws and 3 plastic "fingers" around the perimeter that have to all be pryed out and the cover pryed at the same time. And the engine mount is right there...

Anyway, for anyone else doing it the procedure I used was:

1) Remove battery negative cable clamp (13mm)
2) Remove battery wire from alternator (13mm)
3) Remove Battery light wire from alternator (10mm)
4) Release tension on serpentine belt with external torx socket, and remove belt from alternator pulley.
5) Remove lower, then upper alternator mount bolts (16mm). There are no nuts, you just screw the bolts out, easy.
6) Remove alternator
7) Remove plastic cover from back of alternator as described above.
8) Remove 2 screws holding the regulator
9) Assembly is reverse of removal....
10) Then reset the windows, the clock, and recode the radio

I could probably do it in 1/2 hour now that I have done it once.
I did it all from the top. Haynes said to remove the engine under cover but I did not find that necessary.

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra