If you happen to have a friend with a modded 3DS or a save dongle and happen to have Ocarina of Time, you can use OoThax to get HBL.
If not, you can get Cubic Ninja or a Sky3DS to emulate one of those two games to use ninjhax to get into HBL.
You get only one shot at downgrading, though: If you softbrick, you will be forced to update your SysNAND to 10.4, and you'll have to wait until someone gets memchunkhax2 or snshax working on 10.4 N3DS sysnand.
EDIT: I can tell you for certain that there are no non-XL USA N3DSes that are lower than 9.2, but you have a near-100% guaranteed chance you'll get a 3DS that's lower than 10.3 firmware as long as you don't buy it directly from Nintendo or the person didn't start selling it within the past few hours.