It depends on what that you're doing with those objects with regards to what behaviours and so-on they're running. There is unfortunately no ideal workaround for this AFAIK. HOWEVER: check out the Chipmunk physics port by R0j0hound
It allows 'collision groups' which make this sort of thing easier to control. This, of course, assumes a lot: a) you're happy to install plugions, b) that you're using physics and c) that you don't need incredibly dynamic control of these 'selective collisions'.
Another option that works in some simple circumstances is to have two objects to represent each item, have one with the solid behaviour and the other can be used to collect collision data when solid is not being used. Again, not ideal in all situations.