For thoses interested, here is how to use N3DS ROP installer with the Gateway Blue card :
1- Use 3DNUS to download the v0 of the white list DS cards (EU : 0004800F484E4841 - not sure about US and JP ones, people here will know for sure), DO NOT spoof cia version !!
2- Use the SAME method used to install MSet downgrade (aka DevMenu) to install v0 white list on SysNAND
3- Copy N3DS ROP installer provided page 25 on the DS flashcard micro SD
4- Play all DS games you want
5- When you want to play with your Gateway again just launch N3DS ROP installer and choose 9.x - Launcher.dat from the menu displayed.
6- ...
7- Profit !
Perfect combo
1- Use 3DNUS to download the v0 of the white list DS cards (EU : 0004800F484E4841 - not sure about US and JP ones, people here will know for sure), DO NOT spoof cia version !!
2- Use the SAME method used to install MSet downgrade (aka DevMenu) to install v0 white list on SysNAND
3- Copy N3DS ROP installer provided page 25 on the DS flashcard micro SD
4- Play all DS games you want
5- When you want to play with your Gateway again just launch N3DS ROP installer and choose 9.x - Launcher.dat from the menu displayed.
6- ...
7- Profit !
Perfect combo