I don't think it is possible to use the zoom of the disruptor. You could check the weapons.dat file and try switching some of the secondary fires around. Try to copy and paste the alt fire of the disruptor and put it on another gun.
If that doesn't work I recall a 'zoom' mod for JO or JA on the jk3files site. That could be an alternative.
As for a button for changing firing modes that won't work without code. Same for different stances depending on which button is used. Most guns use Both_stand3 (from the hip) and the disruptor uses Both_stand4 for the shoulder position.
BTW, here is the upload for Dragon 0.9.2: