You'll find a few hatch filling functions on the File Exchange site. For example, the ones mentioned here.
Generally, to apply non-mapping toolbox plotting functions to maps, you'll need to do something like
[x,y] = mfwdtran(lat,lon);
contourf(x,y,z)
and then you'd be able to use hatchfill as shown in the Pick-of-the-Week example.
