Actually yes you can, you will need a game cart entry point so, cubic ninja, ocarina of time + powersaves (remove this if you have an already hacked 3ds) or freakyforms deluxe. You will also need a 3ds already hacked, money on the eshop to buy a 6 dollar dsiware title and a computer
Since one of the requirements is a 3DS that is already hacked, the "+ powersaves (remove this if you have an already hacked 3ds)" is redundant. Also, since he has to have a 3ds already hacked anyway, he can use a secondary entry point which allows some games that people are more likely to have.
--------------------- MERGED ---------------------------
Long time lurker first time poster. Recently got a wii u which I modded fairly easily and got bit by a Nintendo bug it seems...couldn't pass up a deal for a n3ds last night on Craigslist. $100 with an n64! The n3ds is on 11.0, is the method listed above using OOT pretty straight forward or should a novice go flashcart route? Reading up on all these 3ds mods is making my head spin.
A N3DS on 11.0 cannot be downgraded without a hardware modification or the Dsiware method, which requires a second hacked system and a particular DSiware game which you have to system transfer, as well as an exploit game such as OOT. That method is such a hassle that I am surprised that more than a single digit number of people has bothered to use it.
10.6-10.7 can be downgraded using just the OOT. 10.5 or less with a proper browser doesn't require anything else (without the browser, you also need to use the OOT).
Using a Sky3DS flashcart is not complicated, but probably not worth it, and can only play exact copies of retail cartridge games--no eshop, dsiware, out of region games, or hacks. Using Gateway requires basically doing the same things you need to get custom firmware (and like custom firmware, you could stop with menuhax or go all the way to a9lh).