Here is a brief demonstration project for controlling an image sequence with a pose or SmartSkin instead of time.
ImageSequenceToSS.zip 221.69KB 15 downloads
The image sequence shows numbers from 1 to 50 and fades from green to red
The top decal is controlled with the "UpperSequence" Pose slider
The top decal is controlled with a SmartSkin on the "Lower Sequence" bone below the square.
Neither is controlled by time anymore.
When you make a Pose or Smartskin there is a temporary Action created in the Actions folder. That is where you can turn on "Show More than Drivers" and make entries in the "Frame" parameter of an image sequence at certain Pose slider settings or certain bone rotations.