| If you mean door pin as in the thing that pops up and down when you lock/unlock the car, then its quite easy to get off. I had to change a door lockonce so had to remove that pin.
Its quite fiddly and a torch would be helpful. Basically you need to unscrew the door card Torx screws, and prize the door card off (carefully starting from around the bottom.)
Once thats off peer inside the door towards the lock mechanism, and the rod going up to door pin should be visible. It attaches to the back of the lock mechanism. To remove it from the lock, you simply push the rod towards the outer skin of the door (away from the lock), and it pops out. The whole rod/pin can then be removed through the door cavity. I assume you can then glue the new pin onto the rod/pin assembly.
I actually had some photos of inside the door but deleted them from my computer yesterday - typical! | 
