Yeah I've done this.. very neat program too!

Two things I found, to get you started.

1. Use the pic and relay in parallel with the soft Soft -Off wire. I used an omron G5V-1 SPDT type, but you could use a reed relay instead. I know you dont want to use a relay.. but for a couple of bucks... you'll get total isoltation!

2. Depending on your ap, you may need feed back from the pc (floppy power cable example) so the pic doesn't turn the pc off, when it's actually turning it on. Opto isolator for this is a must!

Good luck
J