can new permissions be added to usergroups?

[grumpy]

Admins are exempt from many forum limitations, such as PM limits.

I want super-mods to also be exempt.

Is there a way to alter permissions of usergroups, that are not included in the standard usergroup list of choices?

[JamesUS]

This can only be done by hacking the code.

[grumpy]

I don't mind, if I know where to look for it and what I should be looking for. Any suggestions?