You'll want the window down before disconnecting the rear window switch (in the door panel) so you can remove the clip that keeps the window sliding jaw attached to the regulator.
I usually 1. lower window 2. remove door panel and rain shield (plastic sheet). 3. drill rivets out (you got 4 rivets right? You need a BIG rivet gun to reinstall the regulator) 4. You can then move the black clip on the bottom of the metal channel of the regulator and move the regulator back or forth to remove the window sliding jaw from the regulator. 5, Push the freed window up to the top position, usually the window run channel will hold the window "up", or use a piece of duct tape temporarily if you don't trust it to stay up. 6. Remove the wiring connector from the motor and remove the regulator and motor as an assembly. 7. Remove the 3 screws holding the motor to the regulator, then the motor is "twisted" and the motor is pulled off and transferred to the new regulator.
Putting it back together is pretty easy. Just put the regulator/motor assembly into the door, you will notice the metal tabs that engage into the door to allow it to be held in place prior to rerivetting. Be sure to pull the window back down and engage the window channel back onto the sliding jaw and reclip it. Usually the new regulator sliding jaw will already be at the bottom of travel, so it should go back together as you remember it.
The motor does "know" where the window is after being synchronized. This is done by raising the window using a "soft touch" on the window switch (either front or rear switch), NOT the one-press feature. Raise it up using a soft touch on the switch (first detent in other words), and once the window is completely closed, keep holding the switch position for another few seconds. You will hear a very soft tap from the window motor, at that point it is synchronized. You will need to do this after replacing the motor (when you are done) and also anytime battery power is lost (disconnected or dead battery) you need to do this to all the windows.