XenoDream, being true 3d, is capable of moving/viewing the working image in all dimensions (or that could be 'dementions'). Some other fractal programs may also be capable of this- Terragen can, and probably any other 3d graphic application.

Without getting technical, all that needs to be done is to create two identical images, one slightly rotated or moved to the right (or left). This is easily done in XD by adjusting the X Position of the second image. while keeping the shadows/lighting true. Then butting them together to create one image. You can use PSP or whatever, but the easiest way is to use the Irfanview program to merge the two images using the 'create panorama' option.