How to Install Siri GUI on iPhone 4 and iPod touch 4G Running iOS 5
STEP 1. First you have to download required files for Siri port to iPhone 4 and iPod touch 4G.
STEP 2. Download iFile and OpenSSH from Cydia.
STEP 3. Connect your iOS device to the Computer, then open the folder you have downloaded in step 1 and copy the AssisantServices.framework folder using iPhone Explorer to Root /System /Library/ PrivateFrameworks.
STEP 4. Open Springboard folder (downloaded in Step 1) and transfer all files to Root > System > Library > CoreServices > Springboard.app on your iPhone 4 or iPod Touch 4G.
STEP 5. Simply go to System > Library > CoreServices > Springboard.app and open the .plist file for your iOS device using iFile. .plist file for iPhone 4 will be N90AP.plist and .plist file for iPod touch 4G will be N81AP.plist.
STEP 6. Now you have to add a new property list named assistant to the .plist file, then set its values as YES and set its class as Boolean. Then add the following command to the .plst file:
STEP 7. Now you have to respring your iPhone 4 or iPod touch 4G.
That’s it. You have successfully installed Siri GUI on your iPhone 4 and iPod touch 4G running iOS 5. In order to activate Siri GUI, simply hold the Home button. You should note that you will be able to install Siri GUI only. As Apple server accept data for Siri from iPhone 4S only, so you will not be able to use voice commands on your iPhone 4 or iPod touch 4G.
You can watch the video embedded below to see the steps in action.