ajax.request

I am having some trouble with Cross Origin Resource Sharing and Prototype. I have a simple post request to a foreign resource, and for a simple post request there are some rules that must be satisfied: the Content-Type must be on of application/x-www-form-urlencoded, multipart/form-data, or text/plain, a simple request does not set custom headers with the http Request, and the Server must set the Access-Control-Allow-Origin header correct. with a vanilla JavaScript XMLHttpRequest everything works fine but with PrototypeJS it won't work because it seams Prototype sets some custom headers and I

I currently have a Palm WebOS application that uses an Ajax.Request to connect to a web service using basic authentication. To send the username and password, I simply include it in the url (i.e. http://username:password@ip-address:port/ ) which works exceedingly well, expect for when the password contains anything other than alphanumeric characters (for example, I had a user email me lately who included an "@" and an "&" in his password, and he wasn't able to connect because the symbols weren't getting parsed properly for the url). Is there any way around sending the credentials in the url so