The process would be the same, but I would not trust a flash drive with your only copy of your library. Flash drives are too fragile and prone to loss or failure (I've seen enough dead ones come through here not to trust them).
To use a flash drive or any other volume, though, drag the entire iTunes folder (the _entire_ folder, _not_ just the iTunes Music folder) to your desired location. Then hold down the Option key while launching iTunes. You'll be given a dialog box where you can select the iTunes library you want to use. Navigate to and select the iTunes folder in it's new location.
Note that this procedure assumes that all of your content is contained in the iTunes Media/Music folder. If things are scattered around your drive, moving them becomes much more complex.
Once you get things moved successfully, be sure not to launch iTunes with the external drive not mounted or iTunes will default back to the internal drive. If it does, though, just mount the external drive and launch iTunes with the Option key again.
Thanks...I presumed it would be the same, but I appreciate your input.
Another question, though....if I add more songs to the library in the future, obviously I must have the flash drive inserted before starting iTunes ...but will the "re-direction" work for new music, also?
And another question -- Home Sharing with the other occupant's MBPro and the iPod should still work?
And, a Third question -- can I erase the entire iTunes/Music folder from the internal drive once I know the external system works?
PS: Only copy? No. Been there like in 1982 -- redundacy was a virtue then; today it is a must! But it still bears your repeating the caution, yes!
Yes and yes. Everything that works in ITunes will work no matter where the library is located, so when you add new music, it will go to the flash drive and Home Sharing should be no problem.
As to the third question, once you have confirmed that the library works from the external and you have followed my instructions, not the ones from Apple that just relocate the content, then yes, you can delete the entire iTunes folder from the internal drive.