Unfortunately there was never a 1.3 release of XDoclet ever done so there is nothing we can grab to do an update to the XDoclet lbiraries that ship with MyEclipse.
If you do decide to build it from CVS, you can manually replace the XDoclet libraries in the XDoclet plugin under MyEclipse and then go to the XDoclet preferences in Window > Preferences > MyEclipse > XDoclet and refresh all the metadata and code assist information.
I know this is a far from stellar solution, unfortunately I can’t offer anything else until the XDoclet team does an official 1.3 release (atleast I don’t see one anywhere on the site).