You are able to program 1999 MERCURY MYSTIQUE Key by yourself if you have two original working keys that start your vehicle. The new key will first need to be cut to match your original at an automotive locksmith or the dealership. Once the chip key is cut, you can use the printed programming instructions that we send to make the key work for your vehicle. The instructions are very easy to understand and can be performed in less than a minute. If you only have one or you lost all working key for 1999 MERCURY MYSTIQUE , the programming can only be done at the locksmith or dealership that cuts the key for you.