The Code

Instantiate and set options

window.addEvent('domready', function(){
	new FormCheck('formular', {
		display : {
			errorsLocation : 0,
			indicateErrors : 2,
			showErrors : 1,
			addClassErrorToField : 1
		}
	});
});

CSS rule

.fc-field-error {
	border : 2px solid #800 !important;
}