Whittling Down A Murderjack

[Palanan]

I'd like to use a murderjack (http://archive.wizards.com/default.asp?x=dnd/fw/20040828a) in a forest-based encounter, but CR 9 is much too high for what I had in mind. Is there a fairly easy way to shave it down to about CR 4 or 5? Or is there a similar creature at that CR which already exists?

[Fouredged Sword]

Cut it in half. Half the HD, half the sneak attack, -2 to all stats. That should be a good start.

[atemu1234]

Remove abilities, hit dice, scores, skills, etc.