Thanks again LOU!

Okay, if any brave soul would like to give this a shot, download it here:

http://www.fscaptain.net/downloads/CS727_Pressure_Fix_Beta1.zip

It's a zip and contains a readme.txt file to explain how to install it.  It's a relatively simple thing to install if you are familiar with extracting a folder from a zip and making a one-line change to your panel.cfg file.  If not, don't bother with this.

This should be safe and easy, but it is a beta, so be cautious.  Back up your panel folder first.

After installation the pressure controller should work pretty much as Lou has described above.  Briefly, this works for me:

1.  On the ground, your doors will be open and the airplane unpressurized.  As soon as all doors are closed and the packs are switched on, and there's a source of bleed air (external, APU, or engines) the pressure controller starts working.  It will try and drive the internal cabin altitude to equal the goal you set at the rate you select.  Relief valves will kick in if cabin pressure exceeds external pressure, or the differential exceeds 9.5 PSI.   The relief valves are brutal in they will cause a sudden pressure change.  Try and avoid them kicking in.

2.  Before taxi set your goal at or slightly below field elevation.  Setting it above may trigger the negative pressure valve.

3.  After takeoff once you have established a climb on autopilot, turn your attention back to the pressure controller.  You will see the cabin pressure steady at departure field elevation but the differential will be rising as you climb.   Set your desired cabin altitude at cruise now and adjust the rate to 500FPM or so (straight up arrow on the rate knob.)
Now the differential will rise slower as the cabin climbs, but at a lower rate than the airplane does.

This pressure controller is set to allow a cabin altitude of around 8,000 feet at a pressure altitude of 35,000 feet with a differential of about 8.5 PSI at that setting.  Do not set your cabin altitude so low and fly so high that your differential exceeds 9.5 PSI or you'll blow another relief valve and there will be consternation in the cabin.

4.  At start of descent, set your goal down to about the field elevation and your rate at about 300FPM.   In actual practice the F/E would set it to field elevation plus 1,000 feet and then play with it to insure a low differential (below 1.25 PSI) on landing.  But we don't have a dedicated F/E and we don't want to have to play around with this while we are on approach.  So set the field elevation, or a little below, and let it do its thing.

5.  On landing your differential should be less than 1.0.  You can further adjust it down to almost zero before you open the doors.

Let me know if something doesn't work right.

Enjoy!
Dutch