A mounting structure enables a portable remote control device, that operates a load control device of a wirelessly controlled lighting system, to be mounted to a vertical surface (e.g., to an opening of an electrical wallbox). The mounting structure comprises a mounting fixture for attaching to the vertical surface, an opening sized to receive the remote control device, and a flexible leaf in the opening that receives the remote control device. The flexible leaf may project upwardly in the opening for receiving a flanged recess of the remote control device disposed on a rear surface of the remote control device, whereby the remote control device can be slidably received on the flexible leaf and when fully received on the leaf is retained in position on the mounting structure such that the remote control device is framed by the opening in the mounting structure.