Run itunes off external hard drive and keep settings

I have an imac which has my consolidated music library on it. I also have a macbook which i use while traveling. My itunes is about 130 gigs, which is fine on my imac, but too big for my macbook. in the past what i have done is just put everything on my 80 gig ipod, and then do the manual setting in itunes so that, if i get new music while traveling, i can put it on the ipod. anyway, that ipod was stolen and now i have a nano. So what i want to do is somehow copy my itunes from my imac onto an external hard drive, and then run itunes off that from my macbook. the point being to have my whole music collection there. The problem is that i cant seem to keep all my ratings, play counts and settings and stuff, the macbook doesnt recognize the setting file when its on the hard drive. Is there a way to do this? I tried changing the iTunes music folder location to the folder on the hard drive, but that did not make the songs appear in itunes on the macbook.

In addition, what id like to be able to do is, when i come back, copy the itunes from the external back onto my imac with all the new ratings, play counts, and music.

Message was edited by: poil66