I found this article outlining how to copy the iTunes library from one computer to the other named iTunes: How to move your music to a new computer here:
Specifically the External drive section.
It outlines how to copy the entire iTunes library but you only want some of the files to be transferred. When you get to step 2, rather than copy the entire iTunes library to the external drive, find the music you want within, and copy those files to an external drive.
When everything is copied to the external drive, plug that drive into the other computer and use this article iTunes: About the Add to Library, Import, and Convert functions: http://support.apple.com/kb/HT1347. Specifically the Add to Library section to add the songs to that library.