There was a tutorial somewhere on the net that gave instructions on how to create the "mirrored ball" technique in Bryce, then use a free plugin that you could use in photoshop to convert it to equirectangular image. The trick was to place the ball at the right height in the scene and have the camera looking down directly over it. This could possibly be adapted for Poser, and would look great rendered in Lux using Pose2Lux.

Daz Studio 4.8 and 4.9beta, Blender 2.78, Sketchup, Poser Pro 2014 Game Dev SR5 on Windows 8 Pro x64. Poser Display Units are inches