Once you get the Key of the bluetooth device in windows, you can simply go to settings, bluetooth, and get they key, thats the easy part.
The difficult part is to change it on linux, I use ubuntu and the way I did it was:
install gksu to get administrator permissions, just put this command: sudo apt-get install gksu
once installed you have to press ALT+F2 and type gksu nautilus (just be carefull to only change what you have to, otherwise you can damage you OS.)
Now, go to the specific location of the file following the above answer path, there you will find a file called Info, open it and change the key.
restart the bluetooth or restart your pc and done.
Sorry if bad english and grammar, I was too lazy to check it.