eyeing it is not very hard i do it with my urbans, there was a good site to follow instructions if its your first time, just remember to tape off the drill bit so you dont drill to far, fill the old holes with epoxy, and put epoxy in the new holes before you mount the bindings
To become old and wise...you must first become young and stupid.
i do the same thing. i mounted some salomon bindings on my crap skis by just eying it. it shouldnt be that tough but like he said make sure you tape your drill bit so you dont drill to far in and measure twice before you drill