It is as easy as removing the current driveside of the crankset, removing the granny, and reinstalling the driveside of the crankset. Adjust the inner stop on the front derailleur, and you are good-to-go!
When time & budget allow, you can change the derailleurs (I prefer having a long/-er cage regardless of the setup because it allows future flexibility in drivetrain components) if-and-when the desire/need arises.