Download the latest version of TinyUmbrella from here to your Desktop.
Double click the downloaded package file. Follow the prompts to complete the installation.
Double click to launch TinyUmbrella application from your Applications folder.
Connect your Apple TV to the computer via a micro-USB cable then select it from the list of Connected Devices on the left.
Click the Save SHSH button.
Once completed you will notice a new entry in the Saved SHSHs for Apple TV list confirming the successful save of your SHSH blobs.
**Thanks to semaphore for his work on this tool!