BuddyPress.org

The only way I know to do this, is to log in as an administrator, and then visit the member’s profile edit url (/members/username/profile/edit). You can then edit the fields.

Admittedly, this is clunky. I was toying with the idea of writing a plugin to make this easier, but I’ve also heard talk that this may be addresed in 1.3. Someone else might know more.