go towards box/line at an angle, lock handbrake on (with clutch in rwd) let back end swing round and just before/in box let car roll back but make sure you catch the front end before it swings round to stick you into a 360 spin.
pretty easy when known - and in real life too as u know i know:P
very very very good video here! Love the HD, the FPS is amazing and definatly giving praises to the driver for doing a perfect "autotest" run!