I'd go with gogodr's solution, it'll be the simplest for you - BUT ONLY IF you just request public ticker data, you should in NO CASE send private user-data (passwords ect...) through 3rd-party proxy-services.
If you want to read more about JSONP and how to evade the cross-domain issue for JSON-requests, you can take a look here: http://en.wikipedia.org/wiki/JSONP (or google for JSONP)