TWL_FIRM MUST be sig patched before this will boot! The new patches to TWL were recently added to rxTools and should make it's way into a nightly build soon. The sig patches added also patch out DS Cart White List and save chip detection. So if your DS Flashcart already works thanks to that patch, then you don't need this. rxTools isn't specifically needed. If you happen to have a prepatched TWL_FIRM installed, that will work too. Note...
TWL Slot-1 Launcher (First custom DSiWare app!)