Ok I researched it again
First, set up xmms to play a CD whenever you type the command:
xmms -p /media
Now go to Control Center, Periphals, Storage Media
Under Edit service, change icon to speaker )))
change name to "Play in Xmms"
Under Available medium types, click on Audio CD
Click the arrow button to have it show up under "Display service for"
In the command box, type "xmms -p /media %u"
insert a CD and choose "Play in Xmms"
if it works, re-insert CD and choose always use this action
I do something similar for Xine and DVD playback.