Be warned my Collage Toolkit does not support the automation of transforming images Skewed, perspective or even rotated some. You can do that type of of transforming with the Interactive Populate collage script for it put you into an interactive transform step after placing in images positioned and resized. Fullly automated population scripts do not. However Populated collages are still Layered files or documents and Images layers are smart object layers that can be transformed and tweaked after the scripts populate your templates.
In the example I showed no skewing or rotation was done. The image was just placed into the document to cover Alpha channel Image 1 mapping squarely then the alpha channel was used to mask off the excess. That is why it looks skewed. However in reality in the case it not it just looks like it is skewed because of the masking.
This is what the interactive transform step look like. I just accepted the squarely placed image as is for it looked ok to me.
I could have transformed the image If I wanted too. To something like this:
