I think the cube rotating system is fine, I had more troubles was assigning the jump item.
I think it could be improved this way (just my opinion): with keyboard could be Tab or Left Shift + one of the arrow keys to select the specific item and WASD to assign it to the position (without having to freeze/pause the game). Same thing with a controller but with L1 + A, B, X or Y and the D-Pad.