To make a discrete approximation to a mask using approximate
HEALPix pixels, do
healpixrast.sh <polygon_infile> <Nside> <polygon_outfile>
where Nside is the desired HEALPix resolution.

To generate an output file in FITS format that can later be read
by the HEALPix software, do
healpixrast2fits.sh <polygon_infile> <Nside> <fits_outfile>


Polygon files of the approximate HEALPix pixels are located in
the healpix_polys directory for resolutions up to Nside=32. 
Files for higher resolutions are available at
http://space.mit.edu/home/tegmark/mangle/download/data.html