This piece was done for an Elvis tribute book called Graphic Elvis put together by Liquid Comics.
Specifically this was for the 'What Ifs' section of the book that suggested things that could have occurred in Elvis's life, but didn't. I got paired with him playing with the Beatles which was awesome.
The book is currently available in a 2,500 limited edition hardcover and should be on mass market paperback soon. Hardcover available on Amazon or Liquid's site.
Here's an article about it on USA Today.