Changing to a new frame is pretty easy but the simplest way I've found uses a bit more code than it used to. If FU and FV are the first frame UV coordinates, and EV and EU are the second, 'SPANIM controlN,"UV",-delay,FU,FV,1,EU,EV,-delay,EU,EV,1,FU,FV' will play a two-framed animation.