Mount Bindings

I'm new to the group and hope the flames will be kept to a minimum. My 6
year old was skiing on a pair of tiny Elan's which have relatively new and
in excellent shape Salomon 300 bindings. I managed to get a great deal on a
new set of K2 Magic from a Sports Authority ($50) and want to use the 300
bindings on these K2's but with the exact same boots. My son's weight has
not changed much since last season.

This binding simply use 4 screws in the back and 3 in the front. Can I mount
these bindings with the exact same measurements (distance between front
binding and back binding) from the old ski but percentage out for the
correct location on the new skis (110's)? The local shops want $50 just to
mount bindings because I didn't buy the boots or skis there. I know how to
adjust bindings for the additional weight and skill level and check for
motion etc... but need to know the specifics of drilling (measured depth)
and glue (what kind?).

Any help is appreciate. Please save the "pay the $50" flames. I'd like to
know if this is as simple as it looks.

Cheers