i think you can try to improve the scanner speed in ishow to see what happen, ie. 20k pps. i think ishow should have this ability to output higher speed than 50k pps.
connect your x/y dac to scanner driver board, and connect your r+/g+/b+ and ground to r/g/b laser module, it will work as you want. that is to say: pin 1 and 2 to scanner x and y, and pin 5/6/7 to r+/g+/b+
If quickshow have Japanese version. and output Japanese to the laser? and i have try to write Arabic to output to laser, it looks cant output correct Arabic.