Sprites on Mask?

I am currently working on a project which involves particle system that morphs its shape to create different figures. It is somewhat similar to the school of fish showing the directions on Pixar's "Finding Nemo", however it does not require 3D.

Using text on path with a wiggly selector modifying the position I am able to scatter the text elements around, reshape the mask and then bring the elemants back to make a new shape... howevever in this project the particle elements have to be graphic sprites, not the text.

Is there any way to substitute text with graphics? Or is there perhaps a 3rd party plugin that could give me enough control over particles to reshape the system?

Any help appreciated, needless to say, as usual in the industry it is rather urgent.