By default, clerics get 'channeling' of positive or negative energy, rather than turn/rebuke/command.
For a cleric channeling positive energy, this allows them to heal allies within a 30 foot radius of the cleric for 1d6hp/2 cleric levels. Alternately, they can deal damage to undead equal to 1d6/2 cleric levels with a Fort DC of 10+ the cleric's charisma bonus + 1/2 the cleric's level. Paladins and Oracles of the Life mystery also have access to this ability.
Clerics who channel negative energy can harm living creatures or heal undead in a similar manner.
Standard 3.5 turning and rebuking are still available as feats, dependent on having the proper kind of channeling.
So, parties with clerics do tend to have a bit more staying power than their 3.5 counterparts, and direct damage to undead can certainly be useful, though I have seen a fair amount of Pathfinder clerics take the Turn Undead feat in undead-heavy campaigns.
Paladins also have an increased Smite ability that is particularly effective against undead, so that is something to consider as well.
Pathfinder has also increased the power of undead in some ways. You may wish to take a look at the monster section of the
PRD and compare specific undead from the adventure to their Pathfinder counterparts.
In general, a Pathfinder party will be slightly stronger than a 3.5 party, so if you intend to use the adventure as written with some ad-hoc Pathfinder conversion, you may wish to slow level progression. If you're interested in a full-on conversion of the adventure, then the baddies may scale a bit better with the PCs.
Oh, and if you're considering placing the adventure somewhere in the Pathfinder/Golarion setting, I would highly suggest
Ustalav.