Scripting RGB channels for layers

Question

When you double click on a layer in a Photoshop document, you can set each RGB-channel under "Advanced Blending". How can you script this?
There was quite a similar question regarding CMYK-channels, where MarkWalsh was recording an action. However, I'm still stuck with turning this recorded action code into JavaScript code. And I can't find any hints in the "Photoshop CS4 JavaScript Reference".
http://forums.adobe.com/message/2308538#2308538
Any idea?

Answer 1

Marks code is using the script listener plugin, here is another example...
advancedBlend(false,true,false,80);
function advancedBlend(RED,GREEN,BLUE,opacity) {
  function cTID(s) { return app.charIDToTypeID(s); };
  function sTID(s) { return app.stringIDToTypeID(s); };
    var desc103 = new ActionDescriptor();
        var ref52 = new ActionReference();
        ref52.putEnumerated( cTID('Lyr '), cTID('Ordn'), cTID('Trgt') );
    desc103.putReference( cTID('null'), ref52 );
        var desc104 = new ActionDescriptor();
        desc104.putUnitDouble( sTID('fillOpacity'), cTID('#Prc'), opacity);
        desc104.putBoolean( sTID('blendInterior'), false );
        desc104.putEnumerated( sTID('knockout'), sTID('knockout'), sTID('shallow') );
        desc104.putBoolean( sTID('layerMaskAsGlobalMask'), false );
        desc104.putBoolean( sTID('vectorMaskAsGlobalMask'), false);
            var list1 = new ActionList();
   if(RED){
            list1.putEnumerated( cTID('Chnl'), cTID('Rd  ') );
   }if(GREEN){
   list1.putEnumerated( cTID('Chnl'), cTID('Grn ') );
   }if(BLUE){
            list1.putEnumerated( cTID('Chnl'), cTID('Bl  ') );
        desc104.putList( sTID('channelRestrictions'), list1 );
            var desc105 = new ActionDescriptor();
            desc105.putUnitDouble( cTID('Scl '), cTID('#Prc'), 133.349991 );
        desc104.putObject( cTID('Lefx'), cTID('Lefx'), desc105 );
    desc103.putObject( cTID('T   '), cTID('Lyr '), desc104 );
    executeAction( cTID('setd'), desc103, DialogModes.NO );