Even though you made the proc name available to other threads and Tcl interps via the NSV, the proc still only exists in the Tcl interp where it was created. You won't be able to call it from another interp.
Yet another reason why I'm not really happy with tDOM ...
Peter, I've no idea how tDOM goes about creating its procs, but if it
doesn't give you a way to easily repoduce that process in another
interp, the Tcl Thread Extension and/or ttrace might be able to help
you do so.