To use your Gateway, get the arm9loaderhax.bin that Gateway released along with the 4.0 beta (I don't think they released another one with the 4.1 beta) and use it as a Luma3DS payload or boot manager payload (probably renaming it). It is not in the zip file, it's a separate file on the same web page.
There was a workaround needed for using it with the newest version of arm9loaderhax; I don't know if that workaround is still needed.
There was a workaround needed for using it with the newest version of arm9loaderhax; I don't know if that workaround is still needed.