kmc6566

First, sorry if this has been discussed. I have read a lot of posts on the subject. But I might want to try something slightly different.
Here is my issue. I have a key fob that is working correctly but the buttons have worn out on it. And it might be the contacts on the board too.
What I want to do is this. Take the top part of my key with the immobolizer in it and move it to another "used" key fob. Is that something that can be done by me or would a dealer have to do that? I have put my top with a used bottom and tried to program it by using the procedure in the manual. I knew it wouldn't work but gave it a try.
Thanks.