I have run Siri on iPod Touch that was installed using siriport.ru/1.crt, the installation of Siriport is a little tricky I tried many times and at last it was working. It is very easy to install siri on the iPod touch using repo.siriport.ru and siriport.ru/1.crt. Just follow below steps and your ipod touch4g will be running Siri.
You need the following source to add to Cydia (follow below sequence)
Yo need the to visit following website to get the certificate (after source is added)
It may happen that site is not opening in your ipod touch. So open the browser on your computer and go the above mentioned site download the certificate, email it to your email configured on your ipod and open it from your email. If site is not accessible you can Click Here to download 1.crt file.
Your iphone 4 or ipod touch should be jailbroken if not go here to jailbreak. Now Cydia will be available on your spring board after jailbreak.
How to install the Siriport :(Follow below steps)
Add the Source to Cydia
Reboot your device
Go to Cydia > Manage > Sources and your source will be in the list “SiriPort.Ru Repo”
tap it and install.
This will take much time be patient and wait until below screen
Install the Certificate from the website or open from your email. Write siriport.ru/1.crt in your Safari address bar and tap Go a new installation window will appear like below tap Install
Go to settings and activate Siri, if Siri is not there re-install Siri port.