Configuring ejabberd shaper rules using regexp

Question

I'm running an ejabberd server where I need users whose name applies to a specific pattern will have a fast shaper assigned to them. For example, if I have these users: A123 A222 B892 C123

I would like to make all the users use the "normal" shaper, but if the user name is "A*", I want it to get the "fast" shaper. I'm trying to avoid configuring a group and manually adding all the "A*" users to that group.

Ideas?