I wanna put a new humbucker in my ibanez. The one I wanna get has 4 condutor wiring. If i had it installed with standard humbucking wiring (now), could I have it changed (later) to be wired with a coil tab or out of phase later with a switch or something?

Yes.

If it were a single conductor humbucker, then you won't be able to coil tap it.