DO you want to have a permanent drift or just an oversteer on a corner ?
I'm assuming the latter as you want to cope with the unexpected
So...... take the rear tyres up to 10 psi over normal and then go into a large car park in the wet. The back will break away REAL easy !!
Next, to induce it then use the handbrake. Turn in, hold the button in on the handbrake and sharply pull it up and then let it down asap ( keeping the button pressed so it doesn't lock on ) For this to be "realistic" though you really need a friend to do the handbrake as building the skill to operate 2 pedals, steering, gear change and handbrake all at the same time takes practise
FInally .... if you've plenty of space then go faster, turn in and quickly on/off the footbrake whilst keeping the throttle open. The engine stops the fronts locking letting the rears
This doesn't work at low speed and left foot braking is another thing that takes practice to get modulation and effort right.
Best still, find local track, they usually run skid pan testing options adn you learn a LOT more in a car with outrigger wheels or 4-wheel independt auxiliary brakes on a wet surface and bald tyres
Also the tutor can see what you're doing wrong very quickly and advise correction.