I had a friend SSH into my computer once I got it to the bare minimum for that by his instructions and he helped me install it. After that he did some kind of wizardry to have both Gentoo and SUSE both running at the same time without a VM!
Probably possible if you use Gentoo as the base but keep portage off your $PATH. Ultimately a setup like this will end up being dominated by one of the distros since mixing them properly will cause collisions and headaches.