Hi there. I have a Toshiba A70-RX1 Laptop, and was wondering how to go about
installing a USB printer? (Epson Stylus CX4600). I saw a thread here a long time ago about this printer and that it does work. I know something called CUPS is also involved.
Im on Gentoo. I do have a moderate knowledge of Linux, but have never set a printer up before. Before anyone asks, yes, USB printer support is compiled into my kernel. (Not modular). Thanks!

You'll first need to download and install CUPS, the common unix printing system. It is by far the easiest way to go about printing on Linux. Then you'll want ghostscript as well.

Then make sure that CUPS starts up in your daemon array at boot (usually in /etc/rc.d/ you'd type "/etc/init.d/cups start"). I don't know Gentoo, so I am assuming you know how to get those installed.

After that is done, I think this guide will help you just fine (I typed the above to eliminate archlinux specific information in the following howto):
http://wiki2.archlinux.org/index.php/CUPS%20setup

Hope that helps.