For a 4 HD monster, base saves are either 4/3 = +1, or 4/2 + 2 = +4. I think undead have high Will saves, but I could be wrong. If so, however, that'd be: Fort +1, Ref +4, Will +5.
With a 1 Int, it should have 4+3 = 7 skill points. Perhaps Listen +4, Move Silently +4, and Spot +4. Also needs a...