it been very cleverly altered in my opinion. as for being edited in photoshop, might have been psp (but I'd used photoshop, just plain easier imo.).
To make a pic like this you'd need at least 2 pics:
the first would be of the guys face, you can use a cloning tool to cover the eye sockets and then copy and paste the eyes to a new layer. Then further use extra skin from around the guys face for the extra bit of details (ex: his cheeks might have been used)
The second pick would be the hands. You wouldn't need to modify them much at all.
The rest is blending, and to make sure it looks real to everyone they would take it all the way down to the pixels. Complicated but do-able. Next would be the shadowing, this is quite easy you just use a soft round brush set to black and then use a layer blend like soft light or overlay.
It'd take a day up to a week to make an image such as that one (possibly longer).