THIS IS NOT MY VIDEO!
I followed this video on my iPhone 3GS and it works perfectly apart from a few commands, like texting, e-mailing and setting reminders.



written tutorial

1: Go onto Cydia and download iFile

2: Open iFile and click the wireless button on the bottom bar (note: you must have your device connected to your wireless internet)

3: Download the plist for your device on your computer/laptop

iPhone 3GS: Replace N88AP.plist with:
iPhone 4 (GSM) : Replace N90AP.plist with:
iPhone 4 (CMDA) : Replace N92AP.plist with:
iPod 4th Generation: Replace N81AP.plist with:
iPad 1: Replace K48AP.plist with:
iPad 2: Replace K93AP.plist with:

(note: remove the spaces from the links!)
4: On your browser on your computer/laptop go to the IP address given on the screen of your iDevice (note: make sure you include the port!)

5: Navigate to /System/Library/CoreServices/SpringBoard.app

6: Rename the plist you downloaded on your computer and add a 1 before .plist

7: Upload the plist

8: On your iDevice click done

9: Navigate to /System/Library/CoreServices/SpringBoard.app on your iDevice

10: Find your original plist and rename it by adding backup before .plist

11: Find the plist you uploaded and remove the 1 we added in earlier

12: Reboot your device

13: Open Cydia and go to manage->sources->edit->add

14: Add the source [ Register or Signin to view external links. ]

15: Go into the repo and install MySiri's Port for iOS 5.1.1

16: After your device resprings, it will do 1 of 2 things

16.1: If your device asks you to connect to your WiFi just click next, then on the next screen click use Siri, then the next screen click start using this iDevice (note: Don't worry, you will still have all your stuff on the device)

16.2: If your device just goes to the normal page continue to 17

17: Open up settings then go to general->siri then enable siri (note: click the back button in the top left hand corner then click siri again and check siri has stayed enabled, if not reboot your device and enable it again)

18: Go back to the root of settings and scroll down till you find spire

19: In the proxy host box enter [ Register or Signin to view external links. ]

20: Close settings and open safari

21: In the address bar enter [ Register or Signin to view external links. ] and press go

22: Install all three profiles

23: Done! Hold down the home button until Siri appears and it should work

btw: I don't take any responsibility for anything that happens to your iDevice if something goes wrong, do this at your own will.