Refer to this thread:
http://gbatemp.net/threads/release-rxtools-roxas75-3ds-toolkit-fw-2-0-9-2.382782/unread
rxMode is an independent CFW that can boot Gateway's emunand partition. Although it does not patch sig checks so you can only play legit games/cias with it. However it has been updated to support 9.6 on classic 3DS/2DS/3DS XL. (note that this doesn't support n3DS and n3DS has new Arm9 encryption that was fixed in 9.6, so it will be a long time before Gateway will support it. A nand mod would be needed in this case if you wanted to go to 9.6 temporarily to install the new patches. The NAND mod is needed to restore the pre 9.2FW afterwords)
Basically you can backup your current gateway emunand, then boot rxMode and use it to update emunand to 9.6. rxMode supports 9.6 on old model 3DS/2DS/3DS XL units so you can get access to eShop.
Note that this only will work if you have had installed a previous patch from the eShop. If you installed your last version of the patch via a CIA from a rom site, then the ticket is not legit and the new patch that you download will not have the same ticket that 9.5 emunand had.
But if you did, then the ticket is still the same and you can just install the new patch and then restore your 9.5 emunand back to get Gateway access and the newly installed patch will still work because the ticket 9.5 had matched the ticket 9.6 had because it had a legit ticket and eShop didn't change it.
But for users who only downloaded the patches as CIAs in the past, they would need to manually extract the ticket for the new patch after downloading the patch and find a way of reinserting it into the 9.5 emunand image. A complicated process I won't really have time to explain right now. Though if you own a Gateway it would just be easier at this point to install the new updates via CIA which with a basic google search you can find.
I can't link them here since this forum's policies prevent the illegal dissemination of copyrighted material. Just put the right combination of search terms in Google and you can find it in the CIA updates section of said website. That's all I can say.