i did the same with my 4th gen after it got broken into.

i used a 12V solenoid (from my local automotive security store) and connected the cable to the door handle rod inside the door. the power leads were linked to my car starter module. the module has a trunk release feature (for some of the newer cars) that we connected with the solenoid. so everytime you press on the trunk release button on the remote, the driverside door would open.
i was gonna do the same with the pass side so my ex gf would have her own remote, but we broke up. so the pass side could only be opened from the inside (which isn't so bad when you're usually the only one driving anyway)
i didn't use any door popper kits or anything and it still worked very well even in the winter (except for after i get a carwash where the doors and windows freeze up).
that's pretty much sums it up. but if you want, you can get it done at a shop and buy the door popper kit though i'm sure it won't be cheap to get it done by a professional.