[PaulE]

Since your car is a 2000, it has e-gas and you don't need any speed sensors or switches according to this Pelican Parts how to article on adding cruise control. This is what it says about 2000 and later cars:

In 2000, the Boxster's engine management system was upgraded with a new system that used an electronic throttle body (e-gas). This eliminated throttle cables and instead the gas pedal has a sensor on it that controls an electronic stepper motor located on the throttle body in the engine compartment. Because this entire arrangement is completely electronic, the car no longer needed to have a separate, complicated cruise control system. As a result, if you have a 2000 and later Boxster that didn't come with cruise control installed from the factory, then you can install the turn signal switch with the cruise control stalk, run some wires and turn it on electronically in the computer.

I don't know about the cruise control light. the Pelican article doesn't say anything other than make sure the bulb isn't burned out. On the 2003 the light is a little green speedometer symbol to the far right of all the idiot lights, underneath the fuel and temp gauges. Maybe you have it but it just doesn't light up since cruise control isn't turned on?
Sorry picture is upside down, it's right side up on my computer and my phone!