A utility hasn't been released that supports such a feature yet, perhaps an update to Redsn0w in the future will provide such a function, and likely only for A4 and earlier devices.
It depends on the device.
A 3GS and iPhone 4 can be restored to any version (including the iOS6 versions) if you saved SHSH by using Sn0wbreeze.
But for the the A5+ devices, not possible now, perhaps never.
It depends on the device.
A 3GS and iPhone 4 can be restored to any version (including the iOS6 versions) if you saved SHSH by using Sn0wbreeze.
But for the the A5+ devices, not possible now, perhaps never.
No, if Apple stops signing the version he's on the only version they can restore to is the latest one. The cant stay on the same one.
The OP didnt say what iphone model he's asking about so noone can give him a straight answer.