Using mp3tag to embed album art

I'm trying to find a way to embed album art to my collection.

I have around 7000 tracks that are sorted into about 20 genres (custom genres in case that makes a difference). For example...

c:\my muisc\Hip-Hop (Commercial)\dr dre - forget about dre.mp3
c:\my muisc\Hip-Hop (Underground)\aesop rock - 1135.mp3

So far I've added the collection to itunes. I tunes has embedded album art in some of the tracks already for me. The trouble is, around 50% of my music is ripped from vinyl or is simply too obscure for itunes to supply the album art.

Can MP3Tag be used to find/embed artwork into the missing files in a semi-automated manner?

Is there a guide anywhere?