Using an HTML5 Blob, you can get around the same-origin security restriction for Web Workers. The only slight complication is the need to return a Worker-like interface synchrounously. But this is actually fairly simple. Requires jQuery $ for ajax call. IE doesn't permit making workers from blob-urls, but other browsers do.

BlobWorker.js

Worker = (function(){
	var nativeWorker = Worker;
	
	var BlobWorker = function(){
		this.queuedCallList = [];
		this.trueWorker = null;
		this.onmessage = null;
	}
	BlobWorker.prototype.postMessage = function(){
		if(this.trueWorker)
			this.trueWorker.postMessage.apply(this,arguments);
		else
			this.queuedCallList.push(['postMessage',arguments]);
	};
	BlobWorker.prototype.terminate = function(){
		if(this.trueWorker)
			this.trueWorker.terminate();
		else
			this.queuedCallList.push(['terminate',arguments]);
	}
	BlobWorker.prototype.FileDataReceived = function(script){
		this.trueWorker = new nativeWorker(window.URL.createObjectURL(new Blob([script],{type:'text/javascript'})));
		if(this.onmessage)
			this.trueWorker.onmessage = this.onmessage;
		while(this.queuedCallList.length){
			var c = this.queuedCallList.shift();
			this.trueWorker[c[0]].apply(this.trueWorker,c[1]);
		}
	}
	
	return function(url){
		var w = new BlobWorker();
		$.ajax(url,{
				success: $.proxy(w.FileDataReceived,w),
				error: function(s,err){throw err},
				dataType:"text"});
		return w;
	};
})();

It will be necessary to inject some similar code into the worker's script if the worker wants to spawn subworkers...you can just add the extra code to the start of the script string in FileDataReceived.