For Funk Tank and Cube Dozer I used a prop_vehicle_generic entity as a seat.
For the model I used "prisoner_pod.mdl" from Half Life 2, and the script
"choreo_vehicle_ep1_dogintro.txt" in the ..scriptsvehicles folder.
You can change the clamp angles at the bottom of the script, and trigger enterexit via something like
ent_fire vehicle unlock
ent_fire vehicle entervehicle
ent_fire vehicle lock
ent_fire vehicle exitvehicle
Etc.
Bear in mind though (rawwwr) that there's no camera smoothing when the vehicle's parented to your cube or anything, so movement entirely via vscript (10 frames/sec tops) would be insanely jumpy.
Hope that helps 
For Funk Tank and Cube Dozer I used a prop_vehicle_generic entity as a seat.
For the model I used "prisoner_pod.mdl" from Half Life 2, and the script
"choreo_vehicle_ep1_dogintro.txt" in the ..scriptsvehicles folder.
You can change the clamp angles at the bottom of the script, and trigger enterexit via something like
ent_fire vehicle unlock
ent_fire vehicle entervehicle
ent_fire vehicle lock
ent_fire vehicle exitvehicle
Etc.
Bear in mind though (rawwwr) that there's no camera smoothing when the vehicle's parented to your cube or anything, so movement entirely via vscript (10 frames/sec tops) would be insanely jumpy.
Hope that helps 