Overhead is a utility for making maps in non-mercator projections from things you've developed in TileMill.
It works with Mapnik XML exported from TileMill only. Get your
XML by clicking on Project Settings, and the last thing, next to
Advanced, will be an option to view the Rendered XML for your project.
Right-click and save that output to a file and call it
Then, run overhead. It takes a few options.
--bbox: the bounding box. In WGS84 latitude/longitude. Like
--proj4: the proj4 string for your projection. If you only know the EPSG code or whatever, look it up on SpatialReference.org and enter the proj4 string.
--size: the size in x,y. Like
npm install -g overhead
overhead --size=1000x800 --proj4="+proj=sinu +lon_0=0 +x_0=0 +y_0=0 +a=6378140 +b=6356750 +units=m +no_defs " --bbox="-180,-90,180,90" test/default.xml examples/sinusoidal.png
After you're done there, stop sending me that XKCD article.
This doesn't do tiles, because there are no agreed-upon standards for doing tiles in non-spherical mercator projections. TMS and WMS don't count.