There's a PKGBUILD in AUR of xinput, but I think it needs to be with the other Xorg packages in extra, probably even in the "xorg" group. xinput is a utillity that can dynamically change different properties of the X input devices like the ones that otherwise need to be configured in the xorg.conf file or the HAL fdi file. For example, enabling wheel emulation of a trackpoint. You can also use it to enable or disable input devices. -- damjan
