I've replaced the evaporator on my Commander, single zone system. So I don't know it all, but what I saw doing the evaporator replacement, it really looks like the only way to replace the Blend Doors themselves is to remove the entire dash.
The blend doors that had plastic shafts on the early HVAC of this design would break and jam, causing the gears and linkages driving them to bind, skip or break. They usually broke in a way that they didn't shear cleanly, more like a spiral fracture and thus they could still move some, making the diagnosis even harder.
On the later versions and appears the Commander, they beefed up the shafts and blend doors themselves, so they aren't breaking, but those large diameter shafts ride plastic on plastic as their bearing/bushing with some grease in them. Thus the lube can dry up, gum up, etc and the force to move the shafts can increase greatly, resulting in the flimsy plastic gears and linkages breaking or the motors burning out.
From what I've seen on the Commander, and maybe the Dual Zone is different, you have to pull the dash to change the doors themselves, you have to separate the shell, there is NO door that allows the blend door to be removed with the shell all together under the dash. If I'm wrong, I forgot enough about the job after doing it, as well, again I did a single zone, maybe the dual zone is different.
The drive motors, gears and linkages are external to the Shell, many can be gotten to reaching around and under the openings of the dash, difficult and requires lots of contortion, but its possible. There is at least one drive motor for an air blend door that is pressed right up against the safety/crash cage under the dash, there is NOT enough room to remove and replace it without removing that safety/crash cage, or at least unbolting it and tilting it back quite a bit, you have to remove the dash to get to that safety/crash cage.