U dun have to worry about motorbike license.
The runner will assist you by taking the pre-reg number on the car into a motorbike (the runner will provide the bike, dun worry about this at all) and then apply the new number that you want onto the car.
This is the meaning of interchanging number. The pre-reg number on the car will be exchanged to the bike and the new number suppose for the bike will be exchanged to the car.
The cost for doing all this is around RM 1,600 to RM 2,000. That's all. You just need to choose the number you want, then pay for the number plus the interchange fee of RM 1,600 to RM 2,000.