Access which comp gets replaced using PostRenderAction.IMPORT_AND_REPLACE_USAGE?

Question

Quick breakdown:
I'm setting up a script to prepare AE scripts for a film pipeline. What I want to do is render the output as an image sequence, then import the image sequence and render it out to a preview mov for our dailies process.
I've built and installed templates on all relevant machines, but I'm having problems using the Post Render Actions in the script.
When "Import and Replace Footage" is selected as a post render action, it defaults to replacing "this comp". What I need it to do is replace the placeholder I'm creating in the script instead. Here's what I have so far:
    // Main Output Module
   var MLtemplate = "Main_Output";
   // Main Render Settings
   var MLsettings = "Main_Output";
   // Preview Output Module
   var MPtemplate = "Main_Preview";
   // Preivew Render Settings
   var MPsettings = "Best Settings";
   // Setting variable to highlighted item/comp
   var activeItem = app.project.activeItem;
   if (activeItem != null && activeItem instanceof CompItem) {
      // Adding the active item to the render queue and applying the specified templates to the output module
      var theRender = app.project.renderQueue.items.add(activeItem);
  theRender.applyTemplate(MLsettings);
      theRender.outputModules[1].applyTemplate(MLtemplate);
      theRender.outputModules[1].postRenderAction = PostRenderAction.IMPORT_AND_REPLACE_USAGE;
      // Adding a placeholder to be replaced by the footage from theRender's output.
      var depRender = app.project.importPlaceholder("renderPreview",activeItem.width,activeItem.height,activeIt em.frameRate,activeItem.duration);
      depRender.source = theRender.outputModules[1].file;
      // Arbitrarily guessing at the argument for specifying the target of theRender's "Import and Replace Usage".
      // this currently isn't working.
      theRender.outputModules[1].postRenderAction.target = "renderPreview";
   } else {
      alert("Select the comp you want to render first");
Any thoughts?

Answer 1

The postRenderAction isn't an object or a method, it's an enumerated value used a constant. In other words, it's just a pure number value, in this case equal to 3213 for IMPORT_AND_REPLACE_USAGE. It doesn't have any methods or properties, it's just a number that represents which of the four possible actions the function should take after completion.
As far as I can tell there's no way to do what you want using only IMPORT_AND_REPLACE_USAGE. But perhaps you can use the IMPORT action instead and then have the script look for and replace the appropriate comps after it's done rendering?
Refer to page 111 of the CS6 scripting guide: http://download.macromedia.com/pub/developer/aftereffects/scripting/After-Effects-CS6-Scri pting-Guide.pdf