What's you definition of homebrew? If you want advanced things such as piracy, wireless streaming, and Homebrew apps on the home menu, that would require a cfw (custom firmware). There isn't any exploit now on 11.4 that doesn't require any external help, but you can install it with one of these things:
Dsiwarehax: requires second already modded 3ds
Hardmod: requires soldering skills or reliable hardmodder.
NtrBootHax: requires compatible ds flashcart. Easier method for now.
There are no other methods for cfw ATM, but if you're content with smaller things such as regionfree cartridges, emulators, and even rom hacks of 3ds games you already own, you can just download the rpg make player from the eShop and load up rpghax, which is super easy to install and use.