is the site I use for astro stuff. https://finkh.wordpress.com/3d-workflow/
has some instructions which may be a shade out of date; the PDS site changes regularly. You want to find a page with a Data Set Browser tab and then click it to get to LOLA.
For Mars and other worlds, the data is in .img format, which needs a GIS (Geographic Information System) to convert to a tiff file that Mathematica uses. I will tackle those this summer.
If you can live with equirectangular format and don't mind the lack of curvature, you can download .jp2 LDEM files (you will need a converter for photoshop but there are free ones available) and crop to get a grayscale that should open in aspire, after saving as a tiff or png. (both 16-bit) formats. (NASA doesn't seem to mind http://nasa3d.arc.nasa.gov/detail/moon-nearside-farside
) Don't use jpeg as it is eight-bit.