I'm afraid you're not understanding it correctly. The fact is there is no possibility to make Glassfish v3 to work on a NetBeans RCP application. Inside a NetBeans RCP application the class-loading is mandated by the NetBeans RCP classloading architecture, and not by the Glassfish classloading architecture (that is acting just as a library to access the server-side data).
I submitted a patch about two years ago that solved a Glassfish v2 class-loading issue, so it would be possible to get Glassfish v2 to work on a NetBeans RCP application. The patch was targetted to the client-side jars, and you don't need to touch anything on the server side (i.e, you had to apply the patch to the jar in the client-side, but not on the server side).
I didn't try to patch Glassfish v3. It seems somebody else did, without success.
It seems you can also run a NetBeans RCP application inside a glassfish client container (see http://blogs.sun.com/geertjan/entry/deploying_swing_as_an_application) but I haven't investigated that (I don't like that solution).