I have also used a laser pointer to calibrate my rangefinder and it works great.. Been looking for a way to mount it on my graphic for a while..
Best i have been able to come up with is to mount a small prism on the top hole of the kalart rangefinder and then mount a tube going across the top of the camera (with the viewfinder taken off). The laser pointer would then be mounted on the left side, so that the button is where your thumb rests when your left hand is in the strap.

I wouldnt worry about blinding anyone as long as you dont point it in their face.