I think iTunes will only recognise an mp3 disc if burned through iTunes. Either way, as already stated, it is a data disc and the files can be located through Finder and dragged over to whichever folder you want.
I did this the other day when iTunes wasn't recognising my DVDs, so I used Nero to burn the disc instead. Opened the disc on a Mac and rather than trying to open through iTunes, (which I was fairly certain it wouldn't recognise anyway and don't think it did), I opened it up in Finder and then dragged the files to a playlist in iTunes. It copied all the files to the iTunes folder, but the principle applies to any folder you want to copy them to.