Include it in the pay envelope. Add functionality so that names can be continually added by employees. Invite all of the top names to an on-site open house to get to know them and to begin the soft sell. Consider asking former top employees for names. A GM5 program is simple and effective.
Individual managers can do it on their own, without corporate approval.
If you try it you might also find out some interesting things. There will be a higher diversity hire rate than traditional want ads.