I would email them and ask if the keys would fit. I have not tried the following, I don't have a Becker yet, I copied it from this or another forum to have on hand when I do, so maybe someone else can confirm.

Enter the code using the number buttons for your preset station then push mode button.

If you enter the wrong code more than three time the radio will lock up and needs to be left on for as long as twenty four hours, before CODE will come up again.

Turn your ignition switch to on position.
Turn your radio on, code should appear on the screen of your radio.
After code appears, enter first digit of your code.
Wait for first digit to flash.
Then enter second digit, wait for flash.
Then enter third digit, wait for flash.
Then enter fourth digit, wait for flash.
Then push * on your radio to except the code.