I don't have anything written for BeBot specifically, but with think
this module I've written for RINGBot should work pretty nice. The !ban and !unban command needs a hack in main.php to work though. main.php should be in the repository too if you want to see how it's implemented, just have a search for "is_banned". !setlimit sets the maximum number of players allowed in the bot...I'm not 100% what you are looking for, just hope this is helpful
edit: I see that it won't work out-of-the-box at all now...I have a function that gets all members online in Bot.php which is needed. Anyway, minor modifications should make it work