i am not 100% sure, but:
have a look in ~/.kde. there is your personel konfiguration for kde. have a closer look into share/mimelnk and share/services. there you should find the corresponding config files which make kde play the cd's with xscd.
another possiblity: right click on the cd-drive icon and choose 'edit file type' and have a look in general as well as in embedding. (and check the properties while right clicking the items. there could be some stuff too)