Yeah, you'll have to create your own code or find someone who knows how to do that, since your ID is unique to your saved game. Unfortunately, even if you were somehow able to achieve this, you'd still have to worry sbout your Trainers SID (Secret ID). I suspect this too was altered when you used your codes, and it's a whole different degree of difficulty to change.
Honestly, I'd suggest you just keep the IDs at 00000 or use one of the codes that are already known, because odds are you still won't be able to nickname them besides after capture (SID will still be messed up) and you probably won't be able to transfer said Code Pokemon to the newer games (Flagged Pokemon can't be transferred).