It's only a matter of time before there's an OS X version. It might be possible to deform a panorama into a box-map, then stitch it into a spherized image, but I don't know how to use Photoshop to convert the integer RGB data into floating point data, unless the typical HDRI file reads out as plain text (unlike jpeg or other image formats). This means that trying to fake it with a tiff image mapped onto a skydome would result in a dark, washed-out render compared to an actual HDRI.