Hotkeys (and save states, for that matter) are enabled by default, and they go as follows:

Select + Left Bottom shoulder button = Load state
Select + Right Bottom shoulder button = Save state
Select + Left/Right on the D-Pad = Select state number
Select + Start = Exit the emulator
Select + B = Resets the emulator
Select + X = Pauses the emulation and opens the Retroarch menu (press Select + X again to exit the menu and resume the emulation)

Hope that helps. :3