K-x how to get the most dynamic range?

If I want to get the most dynamic range out of the K-x, for a single image HDR photo, what settings should I use? I assume ISO100 would work better than ISO200 with extended dynamic range highlights. I want to take the resultant photo, and generate a pair of additional jpegs, purposely darkened by 1-2EV (boost sensitivity by 2x-4x), and generate a "pseudo" HDR photo with the original, plus another one or two images deliberately made brighter. I think the Pentax silkypix raw converter software works best. Perhaps I could generate 16bit tiffs instead of jpegs, and then use paintshoppro 4 to generate an HDR photo. Is there a better way, or is there any reasonably priced software ($40 or less) to process a one image HDR photo?

I also the K-x in camera HDR option, but I don't always have a tripod to take multiple images without moving the camera.

• Shel, my photos, http://www.sheltx.com/