The HT1449 method just reassigns the desired location for storage of media, not the whole library which is more than just media files. While it would work it can also lead to future complications. What you really want to do is copy/move the user's entire iTunes folder and all the files and folders inside of it to the same location in the other user's area. This will, of course, overwrite their folder so I am presuming there is nothing you want to keep in the new area.
I will say the simple way to do this is to drag the iTunes folder from one user to the other. However, you are likely to encounter all kinds of read and write errors because of file permissions. You may be able to circumvent some of these if you are doing this from an administrator account but you may end up also having to change permissions on the folders from inside the user accounts. I could test this but have something else I want to do this afternoon.
Read the part about changing permissions on the iTunes folder in: https://discussions.apple.com/message/11583914
iTunes: How to move [or copy] your music to a new computer [or another drive] - http://support.apple.com/kb/HT4527Do not confuse moving your whole folder and library with moving just media files as in
iTunes for Mac: Moving your iTunes Media folder - http://support.apple.com/kb/HT1449