gistfile1.js

var links = document.getElementsByTagName('a');
var replacements = 0;
for (var i = 0; i < links.length; i++) {
	if (links[i].href.match(/^(http(s|):\/\/|)(www\.|)kickass\.to/i)) {
		replacements += 1;
		links[i].href = links[i].href.toLowerCase().replace('kickass.to', 'katproxy.com');
	}
}
console.log('Replaced', replacements, 'KickAss links');