In addition to SiriAuth, @StanTheRipper also released AuthGrabber. This program allows you to easily obtain the iPhone 4S keys with your server. Just connect your iPhone 4S to your server and use Siri. The authentication files will automatically be copied into a textfile and you can then either add them to your server or to your older iOS device directly.
Requirements for AuthGarbber:
An iPhone 4S
A UNIX system (Linux, Mac)
Port 53 and Port 443 are open on your computer firewall and your router firewall (If you’re doing this from your home PC)
@StanTheRipper released his modified version of plamoni’s SiriProxy. It allows you to easily set up your own server. You can then take the keys from an iPhone 4S and add them to your server. That way you can use Siri with older iOS Devices.