Tried to look the archives for information about ICQ, but no, the minimum lenght of search is 4 chars! You should give a permission (at least to Members->) to search for 3-letter combinations. And make it possible to surround the search with "'s so that you can search for phrases.
PS. Looking for the ICQ-related messages 'cause wanted to share this: http://omega.uta.edu/~tom/ICQ/