Complete but untested solution incl. the signature replication

override+apply-sample.js

(function() {
	let _old = XULBrowserWindow.setOverLink;
	try {
		if (Services.vc.compare(Services.appinfo.platformVersion, '2.0.*') < 0) {
			// moz 2.0
			XULBrowserWindow.setOverLink = function(url, anchorElt) {
				try {
					if (NOReferrerToNOReferrerFrom.shouldDispatchOverLink) {
						NOReferrerToNOReferrerFrom.dispatchEvent("onOverLink", url);
					}
				}
				catch (ex) { /* no op; log or something */}
				return _old.apply(XULBrowserWindow, arguments);
			};
		}
		else /* if */{
			// newer; future
		}
	}
	catch (ex) {
		// pre moz-2.0
		XULBrowserWindow.setOverLink = function(link, b) {
			try {
				if (NOReferrerToNOReferrerFrom.shouldDispatchOverLink) {
					NOReferrerToNOReferrerFrom.dispatchEvent("onOverLink", link);
				}
			}
			catch (ex) { /* no op; log or something */}
			return _old.apply(XULBrowserWindow, arguments);
		};
	}
})();