Fixed Gear Chainring Centering
I want to provide an initial answer to this question with some resources that I have discovered and attempted.


Sheldon Brown's Chainring Centering Guide
Velowood Cyclery's Chainring Centering Guide (Updated)


Basic Strategy:


Loosen the chainring bolts until they are finger-tight
Rotate the chain until you reach the tightest section of the chain
Strike the top of the chain lightly with a rubber mallet until you have loosened this tight section.
Continue to rotate and strike any tighter sections that you encounter, gradually softening your blows on subsequent strikes.
Once your chainring is centered and no more tight spots are observed you can tighten the chainring bolts in a star pattern.


Troubleshooting:


If after several attempts you can't loosen a tight section there are two things you can check:

Check for a bent chainring / crank, or off-center bottom bracket (suggestions on how to do this?)
Check for an unevenly worn or stretched chain

Use a chain wear tool and measure the chain wear along the entire length of chain.  Lay the chain down on a piece of paper and write down the wear measurements for each area, then crossmatch those measurements with the tight spot.