Unfortunately, they probably need the barcode itself so they can feed it into the computer. Then using a database, get the freq values/codes (which yes you have) into their software for programing the car. It's much like a UPC barcode in stores. The clerk probably doesn't know and could care less what price is printed on a sticker or sign, it's all about what's in the database and they don't know that until they scan the barcode.
That being said, all you need to do is find out is the barcode format they use and convert your values into it a barcode. Basically the barcode "idiot proofs" the process for a technician who [most likely] has very limited RF experience. Their process is probably not a two way system which could easily be subject to technician error (or worse - exploitation). That'd be my guess at least.
Anyhow, if someone has a picture of their barcode tag from a new key, please post it. I can try to scan and decode. If the freq values are in the code itself (we'll compare to the info you have), we might be able to make a corresponding barcode for you.
Good luck!
