Modswapper will create a shortcut on your desktop, which you will use to launch a particular Mod, rather than launching the game from the CD. (though you still need the CD in your drive if you do not have a CD Crack)
Modswapper creates a gamefile.txt file for each Mod, which is a list of the files that the CTP2 program will use to run the game. A modder can make his changes to each of the files - then he will give those files a prefix which will correspond to a prefix that the modder gave to the file in that Modswapper gamefile.txt file. When Modswapper is launched for a particular Mod, it will look for that list of files.
All of the major Mods use it because it is easy to work with, and it also eliminates a couple of bugs in the scenario setup that Activision shipped. It is required to run any Mod...
Located at my website in the CTP2 section under 'Cradle'