got this from smirnoff_rules for you.
2000 306 HDi today. Remove the plastic fuse box cover. Remove the convoluted air pipe. Remove the 4 nuts that hold the steering column and lower it as far as it will go. Sit in the seat (ie you dont have to be laying in the footwell upside down) put your hand in above the column and up through the hole, the switch is to the right, (RH drive car) pull the wire and the switch will come out of the ho
le in the bracket. Afrter plugging a new switch into the loom, push the switch throught the hole, turn on the ignition, keep pushing the switch in (it clicks every time it goes in further) until the brake lights go off. Press one more click. Bolt in column, replace air pipe and fuse box cover. Hard the first time, 20 minutes after you have done it