The multiplexer we are presently using is an MAX4619, digikey part number MAX4619CPE+-ND.
Select signals are connected to the Arduino microcontroller. Input signals come from the RC receiver [Channel 1 (or 2) for the Sail control (smart-winch) and channel 2 (or 1, I dont know if I have these backwards) for the Rudder control]; and from Pololu motor controller from Arduino (Ch 1 sails, Ch 2 rudder, Ch 0 jib). The Select control switches between the RC input and the Pololu input. There are 2 selects for the two outputs (sail, rudder). On our board we are presently using X, Y and Z channels for Rudder, Main Sail, and Jib. Currently the RC channel for the Jib is being shared with the Main Sail, as well as the select. The jib and main sail sail move together in RC mode, and selecting sails selects both the jib and the main sail. As of June 2011this part is in storage and is no longer used as RC control has been moved onto an additional xbee controller.
To build the multiplexer board in small size took 6 people hours.