I haven't tried it, but it appears to be a moonshell plugin for running .ds.gba homebrew from a slot 1 flashcart.
In case you don't know, .ds.gba files are .nds files that have a loader prepended to them so that they can be run from GBA flashcarts with the use of a PassMe or NoPass device. The loader must be removed in order to run the file from a slot 1 flashcart.
This will not allow you to run GBA games or software from a slot 1 flashcart.