Here you can find a download link to the Siri GUI files for your iDevice, as well as the developers instructions for installing.
While at this time the Siri files released will only enable the Siri GUI, the developer has mentioned he has included files which he will be providing instructions for at a later date.If you are interested in downloading these Siri files and installing Siri on your iDevice please watch the embedded YouTube video.
Links:
Dirtech 