ok i had contacted ivan last year for this request and i got a reply from him (which i jus found out searching through my emails) so he guided what to do inorder to make that change but i m not able to do that as i dont know how to go about it or what tools i need etc.
so i will write here his instructions and if any1 here can do that would really be helpful. here are his instructions:

just need to modify the code of MussorgskyAlbumArt class in
album_art_thread.py . It has two "entry points":
1. get_album_art: It is called in the automatic download. It means
"give me one image for the artist-album". It will pick up the first
image found.
2. get_alternatives: Called when the user clicks on an album art. It
returns multiple images so the user can pick one in the UI.

need to reimplement (or create parallel functions for
google) these two functions:
1. __msn_images (that searches bing and get the html page with results)
2. __get_url_from_msn_results_page (that gets the url of each
individual image from the page).

Note that the file has a "main", so you can test it without running
the whole Mussorgsky. Good for development.


also have attached the latest deb file and the source file from the given link above.