Ian, The documemtaion implies this is possible.  You can detect the resume (ON State) in software, so at that point ask for a PIN. You can prototype this with a script very easily.
The VC5090 system power management scheme will be the same as defined in TNT architecture. The VC5090 system has an additional wakeup source not defined in the TNT Architecture and is specific to the Vehicle Radio Computer’s Deployment Scenario. The Forklift Operator would frequently turn ON and turn OFF the Forklift ignition and the vehicle mount terminal should have the capacity to sense this event and trigger the following system states transition:-

When Forklift ignition is turned OFF from ON position, System will enter SUSPEND state. When Forklift ignition is turned ON from OFF position, System will enter ON state.

The Power panel applet would include Forklift Ignition Sense ON/OFF as an additional device in the wakeup list and would allow the user to enable/disable this wakeup source.

Two wakeup sources defined in TNT Architecture, AC_CRADLE_IN, AC_CRADLE_OUT, would be used as Forklift Ignition Sense ON and OFF respectively, since the VC5090 does not sit in a cradle for interfacing to host system/battery charging as seen in Symbol’s handheld devices. Hence these wakeup sources would be removed from the registry.

Paul, Thanks for that, but its not the terminal we want to stop working until we get a PIN but the actual FLT itself. They want to have some way of restricting and monitoring the FLT useage such that only someone who has been trained on the particular truck can use it. Their idea is that if the VC5090 were powered up they could enter a pin and when this is verified it would allow them to start the FLT. Obviously this would involve us effectively being a software switch in the truck's electrical system, and as far as I know we don't have anyway of passing the 24v back out of the VC. IJ