An elliptical version of the standard rectangular select all command, it obviously does not select all as it is an ellipse, but you get the idea...

Elliptical Select All.jsx

ellipticalSelectAll(0, 0, app.activeDocument.height.value, app.activeDocument.width.value, true);

function ellipticalSelectAll(top, left, bottom, right, antiAlias) {
	var s2t = function (s) {
		return app.stringIDToTypeID(s);
	};
	var descriptor = new ActionDescriptor();
	var descriptor2 = new ActionDescriptor();
	var reference = new ActionReference();
	reference.putProperty( s2t( "channel" ), s2t( "selection" ));
	descriptor.putReference( s2t( "null" ), reference );
	descriptor2.putUnitDouble( s2t( "top" ), s2t( "pixelsUnit" ), top );
	descriptor2.putUnitDouble( s2t( "left" ), s2t( "pixelsUnit" ), left );
	descriptor2.putUnitDouble( s2t( "bottom" ), s2t( "pixelsUnit" ), bottom );
	descriptor2.putUnitDouble( s2t( "right" ), s2t( "pixelsUnit" ), right );
	descriptor.putObject( s2t( "to" ), s2t( "ellipse" ), descriptor2 );
	descriptor.putBoolean( s2t( "antiAlias" ), antiAlias );
	executeAction( s2t( "set" ), descriptor, DialogModes.NO );
}