As i've said in the other thread too, i don't think this is an exploit because it's possible to script it, but because it defies the whole puropose of the Nex's reload taking 1.5 secs (that is, balancing the weapons' relative power to one another).
Btw, i tried to make a script myself but it turned out that the game would not accept other commands while the script was acting (maybe because it only worked if i put 8 consecutive wait cmds between nex firing and switching to laser and 8 more for further switch to nex). Which was far more inconvenient than simply bindng nex to MWHEELUP and laser to MWHEELDOWN

Or, it can easily be scripted it so you can do it by pressing the same button twice (right mouse button works very well for this, since there's no real need of the nex's secondary as you can use +zoom)