LDAP Filter

I work for a large school district and we want to offer Filr to all employees. I currently have my eDir ldap filter set looking at a group (got this info from a TID). So rather than have the hassle of adding employees to a group, we populate an attribute named "empid" with each employees employee ID. So if I could have a filter look to see if the user ID has this attribute I think that would work perfect for me. Can anybody lend a hand and help me with the syntax for something like that.

Thanks!