For who want to know :
If you already set up an emuNAND on your new3DS and if you have the "firmware.bin" of the
ReiNand CFW v2, you can easily test the lastest rxTools nightlies with your new 3DS !
Download the lastest nightly here :
https://www.dropbox.com/sh/blmecish9rb1r87/AACOS5s8u0xucXy59vZk6i1pa?dl=0
Copy all the "rxTools" folder in the root of your SDcard and, of course, copy the ninjHAX files too.
If you have a "firmware.bin" in your SDcard's root, delete it.
Create a "data" folder into the "rxTools" folder.
Download this :
https://mega.co.nz/#!cIpn1YzL!vx2qNWK1SBgwpNq14jnDtTNPo6h7kA1ln6xuTGx8Vso
Put the ReiNand "firmware.bin" into the "rei-to-rx" folder and click on "rei-to-rx.py"
Copy this new "firmware.bin" into the rxTools "data" folder and rename it to "0004013820000002.bin".
Run rxTools with ninjHAX, skip the data installation and launch the rxMode !
THIS IS TEST ONLY, remember the wise words of @AlbertoSONIC !
Great thanks to
@thaikhoa !