How do you replace the rear main seal on a Peugeot 405?

wouldn't try this if your an armature, but you remove the gear box out of the car, take off the clutch and fly wheel, or torque converter if auto, there will be a nice shiny output shaft there. the rear main is the seal is going around that shaft just take care not to scratch ether surface or it will leak, put her all back 2gether and your done