Topic: Creating Mask Reveal in AV?

   Can you get me started in changing how the slides are presented? 

What I want to do is reveal each slide with a wipe (a mask) instead of changing the position of the images.  Essentially, instead of having each picture 'slide' horizontally, I want the pictures to remain stationary and use a wipe effect to show them.  Conceptually that would require the slides to be loaded into a single stack instead of a horizontal chain.

I'm looking for help in grasping exactly what about AV needs to be modified to make this happen.