root can set up clamfs any where in the system. However, as a FUSE-based file system, clamfs also permits end users to create their own clamfs. This is a rather neat feature because each end user can determine which part of his/her home folder requires on demand virus scanning.
In order to let an end user create his/her own clamfs folders, the user account must be added to the two groups fuse and clamav. As root, use the adduser command (in Debian-like distributions) to do this. After the adduser command, it is best to ask the end user to log out and log in again for the new group membership to take effect.