There is already a portable version, but I needed to move some stuff around to get it to work right. There are 4 different ways(parts) of the app you can make mosaics with.
Make a Photographic Mosaic from tile collections(images on a PC)
AndreaMosaic 3.32.17 Beta Portable Version
I guess it's freeware... Might be open source. One would have to ask Andrea.