PSP analog settings on Brick

Can someone help in assisting the best way you can play PSP games on Trimui Brick.

I know the function key can be setup to switch between D-Pad and analogue stick but once I switch it to analog stick, how can I use the X,Y,A,B buttons as D-Pad or second analog stick by holding R key (I saw this guy mentioning that on YouTube that that’s the way to play PSP games that requires joysticks on Brick) ?

If someone know how to toggle that part with X, Y, A, B.