I switched from an automatic to a manual tranny about three years ago, and as I recall the switch was mounted under the console alongside the shifter so the shifter had to be in "drive" for the cruise to work. On a manual I think it is tied in with the "backup" light switch circuit. Are your backup lights working? The switch screws into the side of the tranny case and if I remember correctly these are the only wires that run to a manual. If you have a wiring diagram handy find that circuit and follow it backwards looking for a relay somewhere that leads to the cruise control circuit.