What you require is actually fairly simple, assuming you have access to Excel...it's a matter of using the random number generator function within Excel to create codes of any length you desire. Then you can simply copy the codes to any document you wish, thereby providing yourself with a supply of ready made codes that can be referenced as necessary. I can create the Excel spreadsheet for you, and explain the remaining steps required. This method will be quite easy for anyone who has a basic familiarly with Excel...and, we can get it done within 24 hours, assuming our time zones aren't too different.
Thanks for the opportunity,
Rob