skiing hates that snowboards dont have to pay for mounts.. you are going to have to make your own template, shops dont usually give templates away.. probably for liability reasons as much as wanting your $75 per mount.... just like mountain biking, if you cant bleed your ow hydraulic brakes you cant afford to ride...
use thin plastic, strong thin cardboard, or card stock paper to make a rigid template that will be reusable.
start your template with guidelines, vertical and horizontal lines will ensure you mount the bindings perfectly straight. the shop templates lock on and center themselves...this step is very important.... using your best "eye" and precision, mark the holes from your old ski on trace paper and transfer marks to to the template, ensuring the holes are equal-distant from your center lines.
if you followed this far, you have made a template of where the screws will mount your bindings to your new skis, do not drill your new skis until you have TRIPLE checked your marks and measurements.
at this point, using your old skis, find the drill bit that fits perfectly in the old drill holes, the threads of the screws will be wider than the pilot hole. so double check that the last shop did everything properly... once you have the right bit, put it in the hole and mark how far in it goes. its only a fraction of an inch, and again the pro mounts have stops to make sure you dont drill through the bottom of the ski... wrap duct tape drill bit above that mark until it builds up and creates its own depth ring.
once you have really gone over everything multiple times you can mark your new skis and drill the holes out. do everything like your life depends on it... use proper wood glue in the drill holes, put the binding mounting screws in by hand, making sure they all bite in properly, and i always wait 12 hours before shredding.
*measure twice. cut once.
last year i mounted a roof rack on my truck, drilling into a roofs and skis takes balls of steel.