The DS displays Gameboy nicely - of course. The problems with emulating the PSP seem to be great enough that no one is considering it but at least I know how to convert the PSP display. In one screen have the PSP display condensed to fit but in the correct h/w ratio. In the other screen have a zoom in that adjusts the height of the PSP screen to the height of the Dual Screen and that truncates the sides. The scroll option would be one button. You start by scrolling to the right and automatically reverse when you reach the right edge. You only need to hold down one button to scroll where you want. You could also have a position option that lets you set the x coordinates for the scroll. Double press, triple press to retrieve the positions. Kingdom Hearts GBA had a double right to dodge roll so I am thinking that this should be doable and fast.