Like Depravo said, atm the only way is the Supercard DSTwo, when the 3DS gets hacked, then yeah, it'll be more than possible as long as someone makes an emulator, seeing as the 3DS can easily emulate GBA games by nature (although they have some sort of weird system, dunno how it works, but they're most likely emulated).
But yeah, you'll have to wait for a long time until it that, so the easiest way is to just get a DSTwo.