Actually, this XDA Dev gives the original Instructions, which are based on SIM Unlocking via nv_data.bin and this is only going to work on Rooted Devices and you will also need to Extract nv_data.bin and use a hex editor to take the hashes from a number of offsets and find the Password too.
When Prompted, you will be going to need to insert your unaccepted SIM and then Enter the Unlock Code. For more information including Troubleshooting, please haed over to the XDA Developer Forums Thread . Via XDA
Tags: Samsung Samsung Galaxy S II samsung Galaxy S II SIM Unlock SGS II Free SIM Unlock SGS II SIM Unlock App