Rxtools will play all the games you want.
First you need a way to launch gateway without a gateway card, to set up a emunand. Browser exploit, cubic ninja, zelda oot, etc
Then you want to install rxtools and before loading rxmode, install fbi (a cia service system) through injection in the rxtools menu.
Load rxmode, update emunand and start installing your cia's with fbi.
Most can be found, although easy enough to make from a rom dump with a combo of both 3DS Simple CIA Converter and rxtools.
It is very fast at making them.
The only hassle with installing cia files is the sd speed, limited to your card class and the class of the 3ds used. Class 6 for o3ds and class 10 for n3ds. No u is supported so a u1 or u3, class 10 will not make a difference except to your wallet. To be honest the 3ds has really poor speed regardless of the model.