We used to have a '94 Taurus SHO, which had a factory installed keypad entry on the driver's door.
Before we knew of the AV's existance in 2001, we were very close to buying a Super Crew, which was the only truck, which also had this keypad entry option available.
That is the one option that I really miss from a previous vehicle.
You can view a previous post regarding one aftermarket keypad entry HERE
If anyone else has installed this one, or a different one, please let us know.