As the installation of Solaris 8 on x86 didn't succeeded on my old P-133, I almost gave up. But then I tried to install it on VMWare, even though I hate so much (way too slow). It installed without any problem, though I only have 16 colors in graphical mode :(
Time to install some GNU utilities on it, and maybe a XFree server. Of course it was only after the installation that I found out about this site, which explains in detail how to install Solaris on VMWare.