Here is a function that applies the Layer Style Stroke to the active Layer.
You should be able to figure out which settings to adapt to meet your needs.
////// make stroke //////
function applyLayerStyleStroke () {
// =======================================================
var idsetd = charIDToTypeID( "setd" );
var desc12 = new ActionDescriptor();
var idnull = charIDToTypeID( "null" );
var ref7 = new ActionReference();
var idPrpr = charIDToTypeID( "Prpr" );
var idLefx = charIDToTypeID( "Lefx" );
ref7.putProperty( idPrpr, idLefx );
var idLyr = charIDToTypeID( "Lyr " );
var idOrdn = charIDToTypeID( "Ordn" );
var idTrgt = charIDToTypeID( "Trgt" );
ref7.putEnumerated( idLyr, idOrdn, idTrgt );
desc12.putReference( idnull, ref7 );
var idT = charIDToTypeID( "T " );
var desc13 = new ActionDescriptor();
var idScl = charIDToTypeID( "Scl " );
var idPrc = charIDToTypeID( "#Prc" );
desc13.putUnitDouble( idScl, idPrc, 100.000000 );
var idFrFX = charIDToTypeID( "FrFX" );
var desc14 = new ActionDescriptor();
var idenab = charIDToTypeID( "enab" );
desc14.putBoolean( idenab, true );
var idStyl = charIDToTypeID( "Styl" );
var idFStl = charIDToTypeID( "FStl" );
var idInsF = charIDToTypeID( "InsF" );
desc14.putEnumerated( idStyl, idFStl, idInsF );
var idPntT = charIDToTypeID( "PntT" );
var idFrFl = charIDToTypeID( "FrFl" );
var idSClr = charIDToTypeID( "SClr" );
desc14.putEnumerated( idPntT, idFrFl, idSClr );
var idMd = charIDToTypeID( "Md " );
var idBlnM = charIDToTypeID( "BlnM" );
var idNrml = charIDToTypeID( "Nrml" );
desc14.putEnumerated( idMd, idBlnM, idNrml );
var idOpct = charIDToTypeID( "Opct" );
var idPrc = charIDToTypeID( "#Prc" );
desc14.putUnitDouble( idOpct, idPrc, 100.000000 );
var idSz = charIDToTypeID( "Sz " );
var idPxl = charIDToTypeID( "#Pxl" );
desc14.putUnitDouble( idSz, idPxl, 4.000000 );
var idClr = charIDToTypeID( "Clr " );
var desc15 = new ActionDescriptor();
var idRd = charIDToTypeID( "Rd " );
desc15.putDouble( idRd, 0.000000 );
var idGrn = charIDToTypeID( "Grn " );
desc15.putDouble( idGrn, 0.000000 );
var idBl = charIDToTypeID( "Bl " );
desc15.putDouble( idBl, 0.000000 );
var idRGBC = charIDToTypeID( "RGBC" );
desc14.putObject( idClr, idRGBC, desc15 );
var idFrFX = charIDToTypeID( "FrFX" );
desc13.putObject( idFrFX, idFrFX, desc14 );
var idLefx = charIDToTypeID( "Lefx" );
desc12.putObject( idT, idLefx, desc13 );
executeAction( idsetd, desc12, DialogModes.NO );
};