Introduction and Downloads
Part 1:  Setup
Part 2:  Saving and Animating the Props
Part 3:  FS2004 Import
Part 4:  Setting Up Landing and Taxi Lights
Part 5:  Conversion to FSX
Part 6:  Editing Materials and Textures
Part 7:  VC & Appendix


1.  First, we need to add some extra part definitions (i.e. visibilities or animations) to the modeldef.xml file.  This will let us do two things:
   i.  Define animations for FS2004 part names (makes these conversions automatic)
   ii.  Add new definitions for expanded capabilities (taxi lights, etc.).

  a.  You need to decide which modeldef.xml file you will be using.  For a conversion to FSX it is probably located at SDK/Environment Kit/Modeling SDK/bin/modeldef.xml.  For conversion to P3D it is probably located at SDK/Modeling/3DS Max/bin/modeldef.xml.
  b.  First make a copy of this file by left clicking on the file, right clicking and choosing Copy, clicking the white area around the file, and right clicking and choosing Paste.  This will create a copy of the file.  I renamed this copy to modeldef_orig.xml as a backup.
  c.  Open the modeldef.xml file by double clicking it.  If it asks which file to use to open this, choose Wordpad.  Notepad is also acceptable.
  d.  At the top of this file you will see:

<?xml version="1.0" encoding="utf-8" ?>

      click at the end of the <ModelInfo> and press Enter.  We will insert our new definitions here.

  e.  Download this file containing my extra definitions.  Inside is a text file.  Open it by double clicking the file name.  Click once in the text and press Ctrl A (Select All).  All text should become highlighted.

If you originally downloaded this file before 6/12/2019, you must download it again and edit your modeldef.xml file.  You must replace the light_taxi_visible section and add the special_light section.

  f.  In the modeldef.xml file, click the blank line we made.  Right click and choose Paste.  You can add white space with the Enter key if you want more space before or after this section.  
  g.  If you have previously added anything to this modeldef file yourself, you need to check to make sure that none of my part names or GUIDs (the long string of numbers and letters) are identical to someone else's.  I've tried to make them unique, but you should probably check.  Copy a part name from this tutorial (between the <Part> and </Part> tags) and press Ctrl F to bring up the Find box.  Paste into the find box and make sure there are no others.  Repeat until you have done all of my parts.  Do the same thing with the GUID values.
  h.  Save the file.  It may warn you that you are saving in Text Only format - this is what we want, so say Yes.
  i.  Many of the individual definitions will be described as we use them, but there are two basic types that have been added:
    i.  Custom visibility definitions for parts that should be visible only under certain conditions (for example, the taxi light effect should only display when the taxi light switch is turned on).
    ii.  Custom animations for parts that need to move in a different way from those provided by the default modeldef.xml file.  

For a more detailed discussion, refer to Part 7, Appendix.

2.  If your plane is only in FS2004, make a copy of the plane's folder and paste it into the FSX/SimObjects/Airplanes folder.  Other sims will use similar folders.  If you need panels, gauges, etc., install the plane into your sim from the original zip file.  If you are using FSX, you can check to make sure the plane shows up in the sim.  If it doesn't appear, fix any panel or sound issues that may be missing.  We will use the folder in your later sim from now on.
3.  In the plane's model folder you will find a file of type MDL (and filename ends with .MDL if you choose to display extensions).  Copy this file and paste it back into the folder as a backup.  In our example this will duplicate the FS/SimObjects/Airplanes/DC-6B CB-16/model/dc6b.mdl file into something like dc-6b - Copy.mdl.  We should rename it - a suggested name is the original MDL file name plus - FS9 at the end of the name (not after the MDL extension). Using my example aircraft I made it dc6b - FS9.mdl.
4.  Start ModelConverterX (MCX).
5.  Choose Options (menu)

Options Menu

and make sure your settings are set to:

Importer Settings
Use Conditions:  User Specified

Exporter Settings
FSX XtoMDL Path:  If converting to FSX, set the path to the FSX SDK, probably SDK/environment kit/modeling SDK/3DSM7/Plugins/xtomdl.exe (click the blank screen, click the ... button, and browse to it).  If you are using a different version of 3DS Max to compile your own planes, choose the relevant 3DSM folder instead.
P3DvX XtoMDL Path: If converting to P3DvX (X is a number), set the path to the P3D SDK, likely in the SDK/Modeling/3ds Max/3DSM2012_x64/Plugins/XtoMDL.exe (click the blank screen, click the ... button, and browse to it).

ObjectModel Settings
CollapseModelParts:  FALSE  but keep reading.  Setting this to FALSE  keeps MCX from combining all non-animated parts with the same material.  If you leave this at TRUE in some cases this will make your conversion easier (fewer  parts) but sometimes harder (if you need to assign visibility conditions to parts that have been Collapsed into a single part you will have to Merge these into your model after isolating them with this setting at FALSE).  I describe the process in this tutorial with the setting at FALSE, so set it that way.
Remove Scaling:  TRUE   This must be set to true to get working landing lights and VC mouse areas.

FS Related Settings
FS Paths:  Set the paths for the sims you have installed on your computer.
ModelDefPath:  This should be set to the modeldef.xml file you will use for your conversions - the one we added the definitions to above.  

6.  Close the Options with the red X.