gentoo from stage 1 to KDE took 32 hours on my k6-2 400.
Stage 1 to shell takes about 16 hours.
Gentoo is very very nice. I have an intense dislike of RPM based distros :/ I think they are fine if you are consistent with what you do, but the great benefit of gentoo is that if there is a program, or version, you want to install that a 'package' (ebuild/rpm/whatever) that your distro doesnt have yet, your only choice with an RPM based distro is to make an RPM for it, which is not exactly easy, where as to make an ebuild is pish, and not much harder than installing something from src.
Remember, as far as core functionality goes, linux is linux is linux. If USB2 'works under BingleBeep 7' its going to work under 'Flibble 2002'.
If you are planning to use the excellent speedtouch usb modem, I'd direct you to
benoit's driver, much less fking about than the alcatel stuff. The only gotcha is that you need CONFIG_N_HDLC=y set in your kernel. If you get the distro from sf, unpack and cd to that directory, and run doc-linux/doctor/speedtouch-doctor.sh you will get a nice feedout of what is right, and what is wrong with your setup :)