Ok This is a stupid idea, If you are not at all confident in your abilities, dont try it. Once again i know this is a bad idea however i recently was given a new pair of old salomon 420's and aquired a pair of dynastar px's for 60 bucks. All of my local shops charge 60-80 bucks to mount bindings. This is a fucking ass raping and i refused to spend more to mount them than i did total. So this is what i found compiled into one post for anyone else in my position.
This is a thread with several printable mounting templates with included tutorial.
This is a repost from vimeo that mainly is also very helpful to see a diffrent way to do it.
The hardest part is finding the true center of the ski and the worst thing you can do is trust the grafics. Find the actual balanced center of the ski and go from there. I also found that when i screwed the bindings on i got a bit of a gaper gap. What happened is the binding can run up on the screw thusly snugging the screw to the binding and not the binding to the ski. the way i fixed this was carfully clamped the binding to the ski after starting the screws so it was snug then i was able to get a very tight seem. Also insted of plugging the old holes with wood plugs i simply filled them with P-tex. It was easier and theres no reason why it shouldnt work and flex with the foam cored ski, if it was a wood core however i would have pluged the ski with woodglue and a wood plug. I also found that a 9/64 in bit had a much tighter fit than the also suggested 5/32 in bit.