What exacly you need.. when you create new curve adjustment layer to set automatically blend mode to luminosity?
i will explane you how to do on Photoshop cs 5.1 becouse i don't know how it look and work on cs6..
You'll need to find adobe app on you C Drive.
At my pc i find it here:
C://Program Files(x86)/Adobe/Adobe Utilities-CS5.5/ExtendScript Toolkit-CS5.5/ExtendScript Toolkit.exe
Start software.
On image you see 2 arrows.. 1st and 2nd.
On 1st, switch from ExtendScript toolkit to Adobe Photoshop CS5.1(64bit)
On 2nd, copy script to the initial line
and then click green play button..
ExtendScript tool will create a curve Adjustment layer with luminosity blend mode for you..
var idMk = charIDToTypeID( "Mk " );
var desc3 = new ActionDescriptor();
var idnull = charIDToTypeID( "null" );
var ref1 = new ActionReference();
var idAdjL = charIDToTypeID( "AdjL" );
ref1.putClass( idAdjL );
desc3.putReference( idnull, ref1 );
var idUsng = charIDToTypeID( "Usng" );
var desc4 = new ActionDescriptor();
var idType = charIDToTypeID( "Type" );
var desc5 = new ActionDescriptor();
var idpresetKind = stringIDToTypeID( "presetKind" );
var idpresetKindType = stringIDToTypeID( "presetKindType" );
var idpresetKindDefault = stringIDToTypeID( "presetKindDefault" );
desc5.putEnumerated( idpresetKind, idpresetKindType, idpresetKindDefault );
var idCrvs = charIDToTypeID( "Crvs" );
desc4.putObject( idType, idCrvs, desc5 );
var idAdjL = charIDToTypeID( "AdjL" );
desc3.putObject( idUsng, idAdjL, desc4 );
executeAction( idMk, desc3, DialogModes.NO );
// =======================================================
var idsetd = charIDToTypeID( "setd" );
var desc6 = new ActionDescriptor();
var idnull = charIDToTypeID( "null" );
var ref2 = new ActionReference();
var idLyr = charIDToTypeID( "Lyr " );
var idOrdn = charIDToTypeID( "Ordn" );
var idTrgt = charIDToTypeID( "Trgt" );
ref2.putEnumerated( idLyr, idOrdn, idTrgt );
desc6.putReference( idnull, ref2 );
var idT = charIDToTypeID( "T " );
var desc7 = new ActionDescriptor();
var idMd = charIDToTypeID( "Md " );
var idBlnM = charIDToTypeID( "BlnM" );
var idLmns = charIDToTypeID( "Lmns" );
desc7.putEnumerated( idMd, idBlnM, idLmns );
var idLyr = charIDToTypeID( "Lyr " );
desc6.putObject( idT, idLyr, desc7 );
executeAction( idsetd, desc6, DialogModes.NO );
I hope it was helpful for you.. if you need, you can create JSX file to load it in script list of ps..
Enjoy!