In working on a project with my husband, we decided to store a piece of user information in the user's profile. The problem I ran into came from the fact that it wouldn't be the user themself that edited that information, but the admin of the site. I needed to figure out how to edit another user's profile as the admin. It took me awhile, but I found this article from Imar Spaanjaars that explained how to do exactly what I needed.
http://www.spaanjaars.com/QuickDocId.aspx?quickdoc=377
Cheers!