As Bloodmountain said, you can replace either the volume or tone pots with push-pulls - the "switch" part is completely independent of the "pot" part.
If you definitely want to
split both humbuckers (at the same time), you can do both with
one push-pull. To split them independently, or for series/parallel switching, you'll need
two push-pulls. If you really want to get complicated, you could replace all
four pots with push-pulls and copy the Jimmy Page Les Paul wiring (personally I think that's taking it too far!!

).
A word of warning - if the guitar body is thin (like an SG) it won't be deep enough for push-pull pots!