Well...gentoo is designed to take advantage of your hardware, be it old or new. The older/lesser your hardware is, the longer it will take to setup. The payoff, however, will be worth the time spent.

Genkernel will always take a (relatively) long time. I'd suggest that you either config/compile your own kernel (make sure you know your hardware) or get started on a different distro. Gentoo isn't (IMHO) hard to install if you follow the great docs at gentoo.org, but if something goes wrong you could be lost without some more Linux knowledge.

I'd suggest (if you go the route of another distro on which to learn) Slack or DSL. Mandrake, Fedora and the like are (default install) too bloated for such a slim CPU (IMHO), though you could trim them down quite a bit during/after installation. Debian is also a good distro with a fairly bare-bones install.