importantStyle.js

(function () {

    var elCache = [];
    var styleCache = [];
    
    forceStyle = function (el, obj) {
        if (elCache.indexOf(el) == -1) {
            elCache.push(el);
            styleCache.push(el.style.cssText);
        }
        for (var prop in obj) {
            if (obj.hasOwnProperty(prop)) {
                el.style.cssText += ';' + prop + ':' + obj[prop] + ' !important';
            }
        };
    };

    restoreStyle = function (el) {
        var index = elCache.indexOf(el);
        if (index == -1) {
            return;
        }
        el.style.cssText = styleCache[index];
        elCache.splice(index, 1);
        styleCache.splice(index, 1);
    };

})();

// Example usage:
forceStyle(document.body, {margin: '10px', 'border-left': '2px solid red'});
restoreStyle(document.body);

Did you ever get this working considering the usage string is totally a joke and isn't even consistent in the usage of quoting or the tokens? I struggled to even get it working it sure looks like a quickly thrown together wireframe of a function that was never tested but I really liked the idea so was hoping someone had gotten it working.