Bukkit

So I'm using Permissionsex, and I have already added infernal_mobs.commands.  However I'd like my default group to be able to use 3 of the commands (/im help , /im abilities , /im showAbilities).  If I enable the permission for them, they can spawn stuff and use all the commands.  Is there a way to only give them permission for those 3 commands?

I'm new to Permissionex, but I've tried multiple things hoping it would work to no luck, and couldn't find anything on the internet for the last hour, so any help would be great.