Click on the Namgyalma link, it is the Ushnishavajaya practice with a picture of the Deity.
If you look at the banner mantra on the website pages, this is given out for free and empowered. It is hung over doorways etc. I don't know if it is the same one you are looking for.
But the mantra card says:
In the kutagara Sutra it is said that if the crown of one's head passes once beneath this mantra, the misdeeds of a thousand eons will be purified. In the Forceful Waterfall Sutra it is said that to see this mantra once purifies the misdeeds of three hundred million eons.
It sounds like what you are looking for, but I'm not sure.
You can ask at firstname.lastname@example.org
Also, there is a video of the practice on ustream for the long life ceremony for Garchen Rinpoche about two years ago.