Heres an option for gentoo. One of the gentoo developers created an ebuild that will compile/install gcc 2.95 after a gcc3 install. It puts them as gcc-2.95 rather than gcc. I'm trying to get the build to work, but you can grab it from
http://bugs.gentoo.org/show_bug.cgi?id=8491
Let me know if it works for you. Im getting errors trying to do the ebuild at the moment.