For more information about Wacom tablets in general, try the great Wacom tablet HOWTO from Stephan Runkel <runkel@runkeledv.de> : http://www.linuxdoc.org/HOWTO/Wacom-Tablet-HOWTO.html
About the xf86Wacom.so, check Frederic Lepied's <lepied@xfree86.org> : http://www.lepied.com/xfree86
xf86WacomUSB.so, available at ftp://ftp.aros.org/pub