I know that you can process a single raw image in photomatix as well as in CS5 with some good success. I've been trying a new technique and getting, what I think, is much better results. It's simple but requires a few more steps in the beginning.
Open the Raw image in photoshop. I don't think the version matters.
Save this first image as a tiff. That's your mid-range exposed image
Open an Exposure layer in the layers pallet
Change the Exposure to +2 and save this as a TIFF. Make sure that you give it a meaningful name. "+2" will work
Now change the Exposure to -2 and save as a TIFF. Give this image a meaningful name also.
Do the same thing with -1 and +1.
You now have a single image with 5 different exposures all saved as TIFF files.
Open photomatix and process as you normally would.
Let me know how this works for you.