You must do this on forge and you must have 2 people for this to work.
First 1 Person goes into oracle mode (and must stay in oracle mode for the cheat to be complete) and spawns a Ghost/Mongoose (it can be any of the two).

The second person drives the vehicle forward about 5 meters (you must ONLY drive it forward otherwise the cheat wont work) then the person who is in oracle spawns another vehicle and puts it 5 meters behind the other.

Then the person who is driving the first vehicle gets out and has a rocket launcher that the oracle spawns and blows up the two vehicles.

When the first vehicle spawns the person in human form gets on and drives a couple of meters away.

When the second one spawns the pearson in oracle picks it up then the vehicle should start floating. then just go up a ramp then you will float up into the sky until the person in oracle mode drops the second mongoose

You can always swap after you have done the above, and don't worry you don't have to repeat it!