It is not possible to assign a double command (e.g. L1+X or L1+□) to a single rear button. Rear button mapping allows each rear button to be assigned the function of a single other button, but not simultaneous button combinations.

To programme rear buttons, the multi-function button is held down for three seconds, the rear button to be programmed is selected, and then the single button to be mapped is pressed; mapping then affects only one command per rear button.