Martin,
First and second question would be to what extent you are taking out the heater/AC unit and for what purpose? Are you just trying to change out the blower motor or are you trying to pull the whole box out A/C hoses and all? Craig (from Down Under) has a pretty good synopsis of how to take the
center console out of the car but to get the whole heater/AC unit out I would think you will have to pull the entire dash off of the car to access the attachment screws at the firewall. I just took the dash out of my car to do some rust repair to the drivers side floor pan (OK you might ask why but it is a long story) so could maybe give you some pointers and take a few pictures if that is the way you are going.