It's pretty easy to configure under most Linux distros these days.
Some hints I've found:
Here's my XF86Config, though these differ easily.. This works for me with XFree86 4.0.2.
The LCD cannot go over 1024x768, but it's an ATI Mach64 LB controller.
I got mine in the UK from ajp.co.uk - they're pretty lame, but they do acknowledge Linux as an OS, which they claim to support (though they don't seem to know much about). Looks like they've updated their site, and offer BIOS downloads. The Drivers link (as at 30 Mar 2002) offers no links for the 8500C, but there you go ... I don't know what I'd expect; Linux supports everything in the laptop already.
I'm not sure what the story is with video in/out... under Windows, the ATI software can grab video to a weirdly formatted AVI file, but I've not tried anything else with regard to this feature of the laptop.
I find that the 128Mb Celeron 433MHz configuration of the laptop doesn't suit huge desktops like KDE and GNOME all that well; I use Linux from Scratch (Used RedHat 7.2 as a donor distribution) and IceWM as a Window Manager, which offers everything KDE offers, as far as I'm concerned. You are welcome to view my icewm config files.
Update July 2004: For the past few years, this monster has (with 64Mb RAM) been acting excellently as a firewall, with a 3COM 3c59x PCMCIA card connected to my internal 10Mbps LAN. It uses my SpeedTouchConf driver to configure the crappy Alcatel modem under any Linux distribution I can get to run on it (though recent distro's, like SuSE 9.1, Mandrake 10, etc, simply won't install on a 64Mb machine (it donated the other 64Mb to a twin, which is now unused).