I lit everything in the scene using a combination of Movable lights, and an HDRI environment map plugged into a skylight.
For the HRSS tool I just took a screen grab using it, and made sure that it was set to capture it in HDR, and to apply all the buffers with it as well. (keep in mind that the tool needs to have access to all the buffers and that it does not. Unless I am missing a setting somewhere, most of the buffers it grabs actually serves no purpose for the kind of post work I do.) All the glows and flares and the like are done in After Effects, and not in Engine, so I have more control over the look of everything.
If the person from Epic who makes that tool wants to contact me about it, please do, I will be happy to provide feedback.