Protocol Handlers in Chrome via Registry
Support for registerProtocolHandler has now landed in Chrome 13 - http://crbug.com/73710 for more information.
The API you're looking for is this one: https://developer.mozilla.org/en/DOM/window.navigator.registerProtocolHandler
Though available in Chrome, the call doesn't do anything. This issue tracked here: http://crbug.com/44984
Implementation is underway. See this bug: http://crbug.com/73710