There is nothing regarding learning the keyfob to car unit in service manual fro MA/MB/MC, only later radio ones fo GD Jazz/Fit, Civic EP, Rover 6xx with radio keyfobs. Ceiling unit has no intelligence, can be swapped from car to car, but the under dash unit and the keyfob is a linked pair. If you check any description on eBay, they will tel you that you have to know how to learn it to the car.
You can find the articles regarding Renault, or also old Mercedes IR keyfobs, but it is always HW hacking with changing the address/code. Unfortunately you can't find the same thing in dash unit of MA/MB/MC.
I was considering doing a brute-force attack to receiver unit and guess the code of missing keyfob, but it might take a month and there is a high chance of security mechanism to not accept any code after few tries, so...