yo jorge:

it's not a complicated job as long as you have some soldering chops. these pickups are mounted directly on the pickguard (loosen completely or remove strings). remove the pickguard screws, carefully lift the pickguard - holding it near the guitar's body near where the jack is (here it's connected to the hot wire of the jack and the ground wire - try not to pull 'em out!) gently turn it over and you'll see the pickups, wiring, etc. You'll notice that each pickup is connected to a lug on the pickup switch and to the instruments "ground" (typically via the back of the volume pot). Carefully remove the wires for one pickup, replace it with the new pickup (see mfr's instructions for which wire goes to switch, etc.) If you go one-at-a-time wire-for-wire things should go smoothly. You may want to keep the three "ground" wires together for a one-group solder job to a ground point as a last soldering step.
I've had quite remarkable success with DiMarzio Virtual Vintage Strat pickups (heavy blues virtual vintage is my favorite model) I've put these in all my Strats!!
Good Luck.
Jay

: i was just wondering is it hard to replace pickups on a mexican strat. i know nothing about it at all.