[jQuery] validate classbased via ajax request

[jQuery] validate classbased via ajax request

Hello,
my forms are all css class based validated. Now I need to check some on them serverside, so I overload the regular validation methods (or is there a better way?).
    jQuery.validator.addMethod("date", function(value, element) {
        var preValid = this.optional(element) || /^\d\d?\/\d\d?\/\d\d\d?\d?$/.test(value);
        if (!preValid)
            return false;
        $.getJSON(urlDefs.validateDate + "?date=" + value, function(data) {
            var result = data.Data;
            // what can I do with this result?
            // how can I set element valid?
        });
    }, jQuery.validator.messages['date']);
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I might be doing something wrong...
I know there is a remote({}) method, but how could I use it from there? It might work less asynchronously, thus easier...
--
Jan