you can render a cube map easily with 6 cameras at the center of your scene with 90deg field of view (?) you can stitch the 6 squares together in a program like ATI's cubemapgen as for latlong env maps the best option is to use a lens shader that will do the work for you - like the one you linked in your post
problem with the latlong env maps is I am getting the following error : Warning: (Mayatomr.Custom) : C:/Program Files/Autodesk/Maya2009/mentalray/include/latlong_lens.mi: couldn't find shader libraryAPI 0.0 error 301031: call to undeclared function "latlong_lens"Warning: (Mayatomr.Scene) : output data type "rgb_fp" not…