Updating iphone 3gs with downgraded baseband from 5.0 to 5.1.1

[bc03productions]

i am trying to figure out how to update the firmware from 5.0 to 51.1 with a baseband that has already been downgraded. i am able to restore the phone but not upgrade...anything? Thanks

 

[3cit]

your boned. you need to be on 5.1.1 already, or have 5.1.1 blobs saved. which im assuming you dont have have.
unless.... if ios 6 cant be on the 3gs then you just need to download the 5.1.1 and use redsnow to stitch it together with your custom baseband