There's two commands: MAKE MEMBLOCK FROM IMAGE and MAKE MEMBLOCK FROM BITMAP that could be used for that. I suppose setting up a function to add a load of memblocks together in one big one and then saving it out would work. The only problem with that is, the images will not be compressed and the file rather large. Another trick is to have images stored in a zip or rar file. I did a simple plugin for extracting files from these compressed formats with password protection and I also believe there's another zip plugin floating around somewhere too.
Mental arithmetic? Me? (That's for computers) I can't subtract a fart from a plate of beans!
Warning! May contain Nuts!