I don't know if this is exactly what you mean, but i've done this several times. I create a separate playlist for each CD. I import the songs directly into that playlist -- and since the titles remains "Track 1," "Track 2," etc., I put in my own titles for each track ("BLood test 2-1," Blood 2-2," etc.). This helps me when I remove the files from the itunes library, which I do after putting them on my ipod.
Now -- I don't know if they're shown as an audio book. I suspect not. For me it's not an issue, b/c all I really want is to listen to the files. I take them off as soon as I'm done. I actually think this is a pain in the neck and prefer books on tape. But my library is going a lot more to the CD end of things, not tape. So I'm having to adjust. It's just kind of time-consuming.
Hope this helps.