It's been done, but there's no plug-and-play harness.
A few years ago there was another poster on this forum who had a FAST on his 3SGTE-powered MR2 (same engine as your friend's GT4). Might want to do a search on "Toyota", "3SGTE", or "3S-GTE" and see what you get.
I have a FAST setup on my turbo Toyota truck, and it runs great, but my motor is a few years older and a different model number, so I don't think there's a lot in common. I have a B2B system on my motor, and use a common MSD 6 with the FAST box and the stock distributor. Using the MSD's tach output and one of their tach adapter boxes, I'm also able to get the stock tach to work.
He's welcome to email me if he has more Toyota-specific questions; I'm not sure I can hellp him, but I'll be glad to try.
-Jeff
