you might wanna try searching the marine and RV websites. Seems they have all kinds of power setups. I would think that you can hook 2 alternators up together without much of a problem, but wouldn't it be easier to just get an alternator wired for the amperage you need? If you need help, try Mean Green Alternators, I have their 150A in my truck for onboard welding, it hasn't given me a problem yet! You can get get it even higher if need be, but they are pretty expensive. Also, try Premier Power Welder's website as they carry some large alternators for the Toyota.
And, a cheaper alternative to buying one of these expensive alternators, is to have a motor shop rewind your stock one for max amps and run an external regulator, you can probably get about 200+ amps out of the case.
Just a few other ideas for ya...
i live in alberta and all the shops i have talked to said they can't get any kits or anything for my supra and i took out the power steering so i thought i could just put in a second alt. and do some wiring