Okay thats good. We know for a fact that the modules have loaded. Now what I would like to see is the output of 'dmesg' and your contents of /etc/X11/XF86Config-4 file. If you dont mind, clean up the comments of your XF86 file (any line beginning with #) before accepting the post -- they are unnecessary for my purposes -- but dont delete them out of your file. They can become handy when troubleshooting stuff in the future.
This should be where your issue lies. Either you kernel for some strange reason doesnt like your USB root, or your X server doesnt see the mouse on the USB root, because it isnt being told to look there. If you feel adventurous, you can tell X to use the usb driver.
Here is an excerpt from the XFree86 homepage.
There should be a driver section for the mouse. It will more than llikely resemble mine (below), but mine has a imps2 driver (intellimouse ps/2) not usb. Replace the driver name with either auto or usb and you should be okay.
If your mouse is connected to the USB port, it can either be supported by the "Auto" protocol, or by an OS-specific protocol (see below), or as a generic Human Interface Device by the "usb" protocol.
If you have a mouse wheel, make sure you have the last two lines (3 but mouse emulation off, and the ZAxis map) in there, so the wheel works. If you get it working, of course I wont really need your dmesg and XF86Config
Option "Device" "/dev/mouse"
Option "Protocol" "IMPS/2"
Option "Emulate3Buttons" "off"
Option "ZAxisMapping" "4 5"