I've seen reference to a rule that you can substitute standard actions for move actions and move actions for minor actions. I'm having trouble locating it in the books though.

Maybe also worth giving an example of what I have been able to find:
Quote Originally Posted by PH1
Double Move On your turn, you can move twice if you take a move action instead of a standard action. If you take the same move action twice in a row—two walks, two runs, two shifts, two crawls—you’re taking a double move.
It is also probably worth asking up front: does this let you use a move action to continue a power with "sustain minor?" I've seen you can only sustain "a power" once per round, but I'm not 100% clear whether or not this means you can sustain each power once or one power total.