this UDF will do it.

GroupAdd

you can either run it from an admin computer

groupadd("@domain/<remotecomputer>","power users", @domain\<userid to add> )

or via a logon script (this requires a admin password in the script, this makes for bad security)

groupadd("@domain/@wksta","power users", @domain\@userid, "<admin>|<Password>")

Bryce