Seen it on here so many times that I cringe every time I see "biamp" in a title. It can be done but, in general, if you're asking, you shouldn't. Conversely, I encourage this learning experience for everyone and wish them luck. It's rarely simple and easy except if you're using identical amps, which defeats the purpose to a degree. Unless you're dealing with a really nasty load, like Kappa9's, the only benefit over adequate amplification is reducing the electrical reactance of the woofer affecting the other drivers which, to these ears, has only been theoretical.
Won't get into active biamping because that wasn't the question and I'm not writing a book. Not sure if I would tackle the 801's xover without DSP.