Maintaining iTunes library

Ok so lately I have been expanding my music folder and have run into an anoying problem. I have a rather large folder of 100+ gigs so I download my music to a separate folder in order to keep track of my new music. After it is done I put it in its respective folder in my organization scheme inside my music folder. The problem is that this often takes a while to transfer and I would rather not have to wait until it transfers and then manually drag it into my itunes library. Is there any way of setting it up without having itunes consolidate my library, so that the folder would recognize whenever I add any music files to it and automatically add them to my iTunes library? There is a pc application called itunes library updater that appears to do what I want but I haven't found a mac equivalent. Any help would be much apreciated!