So what about a party consisting of the following:

1. A properly thieving rogue with either the feat that allows partial SA damage against undead or a wand of Gravestrike (or whatever the spell is that allows SA against undead).

2. An evil cleric with as much rebuking as possible (Extra Turning, Reliquary Holy Symbol, Nightsticks) as well as Quicken Turning

3. A warlock for ranged damage against undead that isn't piercing, with as many ways of boosting Eldritch Blast damage as possible (Hellfire Warlock, that one rod that boosts it) for targeting any big baddies.

4. A Dragonfire Adept for breath weaponing mooks (maybe with some metabreath feats) as well as auras.

Your rogue conducts the proper treasure hunt (assisted by your warlock where necessary) while your cleric commands some of the baddies to fight for you and your Dragonfire Adept mops up the little guys on your trail and provides some basic support to the party. The cleric could also rebuke the undead you don't have time to deal with.