I looked at some pics of the Toshiba libretto series. I think I see the switch you're referring to on the front (under the 'pointstick'?). that's a slider switch, not a toggle switch; but they do the same thing anyways
the way you describe it, it's just a simple SPST switch (although it could also be a DPST, DPDT, etc. you won't know until you open it up and see). a relay will work the same as the laptop switch (a relay
is a switch, it simply switches automatically instead of manually). hook the realy coil up to your car's ACC or IGN circuit, and hook the switch contacts to your laptop switch. you can buy a bosch-type SPST relay for about $5 at an electronics store (example; radio shack) or auto supply store (example; autozone, pepboys).
to wire a bosch-type relay: connect #86 to your car's IGN or ACC circuit (or any other switched 12vdc source), #85 to chassis ground, #30 to one side of your laptop switch, and #87 to the other side of your laptop switch... like this:
you should hook up another relay to your laptop's power supply, this will cut power when the car is off (to keep you from waking up to a dead battery in the morning
) I wrote a
simple guide to relays in the FAQ emporium in this forum.