Use balance point (marked on skis) as pin line/for positioning bindings. We would suggest a cable binding in preference to the toe-3 pin binding. The cable adds more torsional rigidity to the boot for downhill control (much better for the long wide skis). Also the cable binding is much kinder to the boots.
If you have the chance to borrow a jig and a drill bit with a shoulder, then the job is much easier. Also if you have the possibilities of getting a cable binding, even better still.
From the balance point measure 25mm forward towards the tip and in the middle of the ski, mark and drill the first hole – a drill bit 3.5 mm in diameter, at 9mm depth wrap around several rounds of insulation tape making a shoulder and preventing the drill bit from going in to deep. Make sure that you keep the drill upright.
Screw on the binding with the first screw, not 100% tight. Having first applied a small drop of winter wood glue, proper binding glue would be best if you again have the possibility of getting it. The glue stops the damp and water from getting into the core of the ski.
Place the ski boot in the binding and center the heel on the ski, carefully remove the ski boot, mark the two remaining holes. Slide/twist the binding to the side and drill the two holes, twist the binding back in place and screw in the remaining two screws, also now tighten the front screw.
Now attach the heel plate and a good idea is to varnish between the binding and heel plate, this will prevent the new loose snow from packing and sticking under the foot.