You can use the fullstop key [ . ] and the comma key [ , ] to advance or regress in the order of the photos filenames.
Due to the way that you shot, this results on a pretty bumpy ride on your two closer orbits as the camera constantly looks up and down. I've used this several times before and have concluded that I prefer covering tall objects in a vertical spiral, rather than trying to get complete vertical coverage at each viewpoint all at once (unless you can cover it by using portrait shots, rather than landscape).
You can use the fullstop|comma keys on any synth, but if you'd like to make this order the default for all your visitors who only use the icons onscreen, you can use the [Edit Synth] button -> 'Advanced' controls to switch your slideshow order to filename order rather than Photosynth's default spatial order.
P.S. Try not to post in the official Photosynth team's announcement forum. Cheers!