Button convention

All objects of type function can be bound to a button element.

<button data-name="save">Save</button>

The convention will also look for a function guard member on the ViewModel which by convention is prefixed with can

TestViewModel = function() {
    var self = this;
    this.save = function() {
        self.canSave(false);
    };
    this.canSave = ko.observable(true);    
};

http://jsfiddle.net/3Ajnj/13/

Anchors

Anchor support is not built in to the library because enable and disabling of anchors are not supported by KO, here is a way of doing it

(function() {
    //First make KO able to disable clicks on Anchors
    var orgClickInit = ko.bindingHandlers.click.init;
    ko.bindingHandlers.click.init = function(element, valueAccessor, allBindingsAccessor, viewModel) {
        if (element.tagName === "A" && allBindingsAccessor().enable != null) {
            var disabled = ko.computed({
                read: function() {
                    return ko.utils.unwrapObservable(allBindingsAccessor().enable) === false;
                },
                disposeWhenNodeIsRemoved: element
            });
            ko.applyBindingsToNode(element, { css: { disabled: disabled } });
            var handler = valueAccessor();
            valueAccessor = function() {
                return function() {
                    if (ko.utils.unwrapObservable(allBindingsAccessor().enable)) {
                        handler.apply(this, arguments);
                    }
                };
            };
        }
        orgClickInit.apply(this, arguments);
    };

    //Second make the Convention library work with anchors
    ko.bindingConventions.conventionBinders.button.rules[0] = function(name, element, bindings, unwrapped, type) {
        return (element.tagName === "BUTTON" || element.tagName === "A") && type === "function";
    };
})();

http://jsfiddle.net/xCfQC/13/