this method of projection painting possible?

I’d like to know if projection painting as in these slipgatecentral tutorials is possible with blender: http://slipgatecentral.livejournal.com/26118.html (I believe he is using Deep Paint 3D for this in the video)
I know there is something called “projection painting” in blender, but from what I’ve read and seen I don’t think it’s what I’m after…

Basically, I’d want blender to take a screenshot of the viewport, which I can then transfer into the 2d program of my choice, paint on it, and then take it back to blender and project it onto the uv-mapped model.

Blender’s projection painting can do that, yes; you should be able to find a couple of good video tutorials on it. You need two UV unwrappings: the ‘real’ one to paint onto, and a temporary one made by projecting the view to paint from.

Best wishes,
Matthew