If you only want your player or the guy who is hurt not to enter as driver ,you will need a checking trigger.
Put these in the trigger.
axis a /b : 0
activation : Any body
Repeatedly
Not present
type : none
Condition : nameofguy == driver nameofvehicle
On Activation :nameofguy action ["eject",nameofvehicle]
I think this one will work(it worked for me)
Everytime you (as player) entered the vehicle,then he will be pumped out from the seat.
If you want to use with AI,please do the following,
On the init line of the vehicle,type :
nameofguy assignascargo nameofvehicle
Remove the get in waypoint (if you have one) and place a "move" WP near the vehicle.
In the On Activation of the WP,type :
nameofguy ordergetin true
I think that solves your problem
Haroon1992..............