Is it possible to get a drive key from a damaged drive?

Hi

I have a Hitachi 79 drive which may be damaged, as it doesn't read dvds or 360 games (don't know why its broken). I have a spare BenQ drive (already modified) that I want to put in the 360 where the Hitachi came from. As I understand it, to do this I need to get the drive key from the hitachi, to put on the BenQ, so it will work with the motherboard.

So basically I need to know how to get the drive key from the hitachi and put it onto the BenQ drive. Once I've done this, will it simply be a case of connecting the BenQ to the xbox and it'll all work?

Any help well appreciated

Thanks