Yes, you will have to take one of your 3DS'es and send it to me. I'll keep it safe for you.
In all seriousness, you'll have to update your 2.2 3DS'es to a firmware from 4.1-4.5. You can do it via a ROM with that update with Gateway's firmware 1.0 (IIRC), or use a retail cart that has any of those updates. To see which games have which updates in 'em, check out Pong20302000's website: http://3ds.essh.co/
Any 3DS with firmware 4.1-4.5 will work on Gateway. Happy gaming!
If you are on a firmware lower than 4.1 you can't use a rom with Gateway to update because you can even get into Gateway mode. You need a retail game.