Jeff was a huge help to me getting my mind in the right order to tackle the project and keep the stock systems in check. From there, I had to branch out on my own.
Here is the trick. There is a pair of wires going to the key door lock that disarm the system when you unlock the car with the key. Basically, for a split second it shoots a ground back to the control module and kills the theft system.
All of us with a C4 at one time or another have locked the door with the power door lock, then let the door swing closed while still in the car. Then, you go to open the door and it is locked. So to get out you retrigger the power door lock, or manually unlock, and Beep, beep, beep, beep, the alarm/horn starts honking.
If you put the keyless system on without making a jumper trigger for the key door lock, it will trigger the alarm everytime you hit the unlock keyless feature.
I followed the wires and set up a relay (normally closed) to keep everything in check. When I hit the unlock feature, the relay will snap for a spit second kicking a ground feed to the key lock wire and disarming just as it triggers the actuator to unlock the door.
I mounted the keyless control head and relay in the driver door.
If you get the kit from Mid America, it comes with the relays and complete set up ready to go, and you just follow the instructions. The most difficult part of the job will be yanking your door panel.
Remember, you have a screw under the courtesy light in the door panel as well as under the handle, and under the door lock lever.
Oh, on the hatch, I had to take one side of my module to ground, then the other to the trigger wire on the release switch already in the door panel. At first I just jumpered right into the factory harness for the hatch on both sides, but....it would only let me pop the hatch if the door was open (saftey feature on stick shift cars to keep from opening going down the highway). That was not good, so I went to a hard ground for the feed, then ran it to the switch, and bingo, works like a champ. Come to find out the rear hatch is not in the alarm system, so it can open and close seperate of the door and not trigger the alarm.