I had the exact same problem and finally got it to work. It's kind of tricky since the BV7 can't display 50 or 60Hz settings via component cable.

You need to connect your BV7 via SCART cable first, so that you get a picture and and can navigate through the Wii Setup menu. In the Wii menu you will find the section "TV type". You will see the that the "EDTV/HDTV  (480p)" button cannot be selected since you are using a  SCART connection. Now it becomes very tricky, since you need to select that button and confirm it without being able to see it. 

I put my Wii controller on a coffee table and used a couple of books so that the controller would point exactly on the "EDTV/..." button. I also checked the position that the controller would need to be in, in order to select the "Confirm" button. After having the controller in the correct position, i disconnected the SCART and replaced it with the component cable. Sound should still be there, but no picture. Now select (blindly) the "EDTV/..." button and then the confirm button. You should here the sound from clicking the buttons and shortly after you should get a picture. It might take a couple of attempts, but it will work!

Another solution would be to connect your Wii to another non-B&O flat screen TV via component cable and change the setting there. Most flat screen TVs will not have a problem to display the 50 or 60Hz settings via component cable.

I hope this helps.

Good luck!

Dennis