goodluck with that...I'll download this once it is 1.3!
All of the errors have been patched. Currently though, spawning a mob requires changing a base class which will cause problems with other mods that add mob spawning. Currently, I am waiting for ModLoader to address this issue. Cool stuff will be added once I get the 1.3 version working :).
Sorry about not having this mod updated yet, ModLoader has not yet fixed an issue with mob spawning in the newest updates so I am currently waiting for that to be fixed. I am aware of the patch that fixes this requires patching a base class that could conflict with other mods that add new mobs, so for that reason it is not being used. This mod will be updated the second I can.