I'm running a CentOS 5.7 guest (Windows 7 host), and the Guest Additions mouse driver is sending wrong events for the thumb buttons on my mouse, and no events for sideways scrolling. It's a 9 button mouse (left, mid right, scroll up and down, tilt wheel left and right, and two thumb buttons).
According to xev, the first 5 buttons work like they should, but the thumb buttons register as button 3 and 2, while tilting the wheel gives no events at all. They work fine in the host. I've tried mucking about with xorg.conf, xmodmap, and imwheel, but the events seem to be generated wrong at the driver level. If I edit xorg.conf and remove the mouse inputdevice so X11 is left to autodetect the mouse, the thumbs will register as button 6 and 7, but then mouse integration no longer works, and tilting the wheel still does nothing.
Any ideas what I could try? I've read about xinput, but can't figure out how to get it for CentOS 5.7.