It would be kinda hard to do. You would REALY have to scale the HP back for starters.
I would think about doing 1-2 HP per monster HD. If the creature is unusually tough, maybe 3 hp per. or just add some DR to the creature.
I don;t have any books in front of me ATM so I can't begin to realy look at what would be needed. All I know is, taking straight conversion, Kobolds would be one hella tough opponents in B5 :wink: