Never really had a problem on mine. I'm surrently trying to wear out the rear tyres doing this so I can put on some new ones for the MOT.
Try over inflatting the rear tyres. This should help it loose traction.
Failing that wet or bump surfaces should be very easy to make the back end lock up.
Try removing the spare tire and kit to make the rear lighter. Also less fuel in the car will enable the handbrake if poor to work more effectively.
Other than that you need to turn very tight and the handbrake and calipers need to be in very good condition.
Giving them an overhaul with newish calipers and tightening up the cable should help.
Alfa 166 2.0 Twinnie - LPG and a few trick performance parts