What about the Seeker archetype for Oracle? It states:
Tinkering: ...In addition, at 1st level, a seeker adds half his oracle level on Perception checks made to locate traps and on all Disable Device skill checks (minimum +1). A seeker can use Disable Device to disarm magical traps. If the seeker also possesses levels in rogue or another class that provides the trapfinding ability, those levels stack with his oracle levels for determining his overall bonus on these skill checks.
Just to understand the mechanics, take a Rougue5/Ranger(Trapper)5/Oracle(Seeker)5 what bonus would I get for spotting traps and disable device as each class has half the classlevel as a bonus and only the oracle classlevel has a mechanisms of stacking classlevels, not bonuses?