I'm using a USB mouse and a P/S2 keyboard with a USB convertot... so basically all my input devices are USB.
Everything works well even with the vmlinuz-2.4.20-ide stock kernel I used before compiling my own.
Anyway, if you're looking to compile your own kernel, then follow neenee's advice. At the uhci section, just choose your chipset manufacturer, it would save some kbs to the overall size of your kernel. Preferable include them directly to the kernel, do not add as modules.
Hope this helps