How to use the CustomCheck in TCB Car Dealer

[YoutoYokodera]

Well i'm not a programmer and my english is bad too, so i just want to ask if anyone know how to add the Customcheck for some job to the car dealer?
the only thing i can do now is adding a vehicle and the price

TCBDealer.vehicleTable["sw_bus"] = {
	price = 0,
}