There is this feat:
Turning Immunity
Feat Type: Class Feat
Prerequisite: Baelnorn Level 4
Description: The baelnorn is immune to turning attempts by good or neutral clerics. If rebuked or commanded by an evil cleric, the baelnorn is instead turned or destroyed.
but I can't find the code for it, so chances are it's not implemented. I'll have to search some more...
With current code it would be quite easy to add turn/rebuke immunity.
Edit: Just making sure I understand you correctly. You would like to make a creature turnable/destroyable by good/neutral clerics, but immune to rebuke/command attepts of evil clerics, right? Or should rebuke/command also turn/destroy that creature (like in baelnorns feat)?