13
The best method I can think of would be a module that directly manipulates the XOOPS ban fdield in the database (which means no core hacking- woo). It could then handle advanced banning. For example, the user could drop in an address range, and while in the ban manager it would show it as a range, in the XOOPS -> general preferences, it would log all 200+ IP addresses. Just an idea.
I won't be able to work on it much until after the 10th of July due to some other obligations, but bd if you would like a hand with it, let me know. :)
~Jakob