I do a lot of manual editing of info. Seriously, I do so much because I download a lot of free albums/mixtapes (I don't illegally download music, I really like to support the artists, you'd be surprised how much free stuff there is out there). Whenever the info is greyed out, I put it through an audio converter (I recommend
DVDVideoSoft, it has a ton of useful tools for doing video/music stuff and I use it very often). You should convert it to either an MP3 or M4A file, then it should let you edit anything.