If the BIOS can't see it, then no bootloader in the world will be able to boot off it, that I'm aware of. You could certainly write one, but it would require including enough PCI and firewire support ...
SO I dual boot RH7.3 & XP using GRUB. One annoying thing though, the grub loader sits at that "loading stage2" for around 30 seconds...which seems like an eternity when you are waiting for a reboot ...