This is more or less what I was trying to do with the first transitioning gnomic projection example but I backtracked and tried to make use of this d3.timer() thing. I want to experiment changing the values I give to projection.rotate() and also see if I can figure out how to done rotate it a bit smoother using transitions or tweens or some such thing.
See these other poorly done gnomic d3 attempts:
I pretty much stole the rotating function in d3.timer() from http://bl.ocks.org/mbostock/5731578 which looks much smoother with a spherical (round) projections. I don't really know what I'm talking about yet though and need to do some more research and experimenting.