Thanks Konttori! I had to give it a go right away, and it worked on my N810! Er... a little too well, perhaps.

I opened the image file (.png) with photoshop and made two modifications. I changed the color of the people icon and the color of the 'up' finger-scroll button that appears in the pop-up app menu. I made the .deb file and installed it, then changed to the new theme. At first, only the button color changed, and that was good enough for me, so I changed back to a stock theme and everything seemed to go back as before.

Then, today I re-booted (for other reasons) and when it came back on, first it loaded the knottori boot screen icon, then loaded the 'old' icons on the left. The people icon was now the color I changed it to in my new theme. Again, I thought, ok, that's progress! But I want to go back, so I changed themes, and, well, nothing. Still have the old icons. So I rebooted. No change. I uninstalled the theme and rebooted. I still have the old icons.

This is not a complaint, since I am happily a beta tester, but I would like your feedback and suggestions if possible. I look forward to making some neat themes once the details are ironed out. Thanks again.