You can but it will not be that easy... you need an exploitable game like Pokemon ORAS, Freakyforms, Smilebasic or the other *hax games.
Just Google for these games and buy one them digital or Card AND if you dont own Pokemon Picross you should get it now from the eshop (its free) because there will be a new exploit released based on Pokemon Pricross!
EDIT: If you have one of these exploitabe games drop me a pm I'll give you some help

AND to use pokemon picross expoit you WILL need antoher game (Like one of these i listed because they are Primary exploits (= Primary means u dont need another existing homebrew entrypoint to install it like Basehax (basehax is Pokemon ORAS exploit to run Homebrew)
and pokemon picross (released soon) isnt a Primary exploit unfortunary its a secondary...(secondary means that this Kind of homebrew exploits need to be installed from an already existed homebrew exploit)
Sorry for this loooong post and a bit confused one ;(