[KillerOh]

1st of all, could you say WHICH GAME(s) you've tried with such script?

- For Call of Duty 1, Soldier of Fortune 2 and Neverwinter Nights (1st game plus expansions), the CD-key is stored among all the installed files. So it's basically "inserted" by default, and being so, that's all ok.
- For most of the Pro Evolution Soccer games (At least from 2009 up to 2012), the game will NOT launch if the CD-key is missing from the registry, even using a No-CD patch. So it's a REALLY BAD IDEA.
- For old EA games (Like Medal of Honor series) that requires a serial to install the game AND is stored just after inserting it in the registry will work even if you delete the registry key with the serial (And some will even skip the serial page if a key is already inserted in your system BEFORE installing the game), but don't expect full funcionality (Single player and/or offline experience at most - and crack required). Will work, but not a good idea.

So, to summarize:
- If the game stores the CD-key in the game files: Do the conversion with the installed files and we're fine.
- If the game stores the CD-key in the registry: Add it in the "Registry" section of your script, regardless it works with or without them.
- Regardless how the game store the CD-key, if Online activation is REQUIRED: While I'd rather recommend NOT TO DO a custom installer in these cases (Rather, find a way to split the game in as much as required DVD5's for it while keeping the original installer or use the "Backup" function for STEAM games), you should add the key in the "Registry" section of your script.
DO NOT INCLUDE A NO-CD PATCH//CRACK//SERVER EMULATOR//(WHATEVER SH*T THAT "SKIPS" ONLINE ACTIVATION) IN THE GAME FILES!!!
Even if you don't want to be annoyed to "log in" just to play, it's just NOT a good idea.
BTW, adding a no-cd patch along the game files while trying to do a custom installer is a bad idea.