NetBeans can run Ant build scripts and XDoclet is launched as part of an Ant script, so there's at least one way how you can integrate XDoclet with NetBeans.
Sorry. I haven't used NetBeans. But assuming it can do Ant, it can do XDoclet. I don't know if it has any higher level functions like automcomplete of XDoclet attributes or quick attribute templates like some of the other IDEs do, but that isn't a necessity. Maybe some Netbeans users can comment on their experiences with XDoclet...