I have kept this pretty simple so you can see what I have done.

If you want to use a larger graphic for the transition, its quite easy.  Make sure your graphic is an even size, easily divisible by 4 to give 4 even pieces.(I sized my graphic at 400 x 400)  Copy your main graphic to a greyscale and insert that into a container as before.

Slice your main coloured graphic with the image slicer into four same sized pieces.

Insert a positioned MAIN container, positioned, horizontal left, top 0, insert your positioned containers and scrolls(top left part) exactly the same way as you did the original transition(40 containers).

Then copy and paste the MAIN  container, just changing to top right, and change the graphic to the top right part.

Repeat for the bottom left and right parts.

 

You can even add some snow if you want.!  I just placed a positioned container, inserted a background of snow, in exactly the same position as the large container sized at 400 x 400, making sure I dragged it down so it snowed over the images!

If you want to slow your transition down, make the pixels per second half of the pixels per move, i.e., if your graphic width is 200, make your pixels per move 200, and pixels per second 100.  I dont think it is quite s smooth that way, but its up to you.

 

Hugs

Lin