I have heard of it being done with the door card in situ Mike but I wouldn't attempt it myself. Especially when it only takes a few minutes to remove the door card and do the job without the risk of damaging trim.
By loosening the clips and the screws near the little speaker, I was able to remove the plastic trim that runs around the window frame. Everything is now happily back in place with the replacement mirror in situ. Sometimes small hands come in use.