One of teh devs will have to respond to this.  Consider my post a bump.

At a minimum, be able to navigate the rows of tabs in some way with tabs or arrow keys and be able to tab or arrow through the options available on the pages. Having letter key shortcuts you often see on Windows menu items would be most helpful. For example:

Use Alt to activate top tier tabs and use left/right arrows and/or letter shortcut keys to select option.

Use left/right arrow keys to scroll through the second tier tabs and/or use letter shortcuts.

Use tab key to move through the various options on each page.

Once selected by a tab key, be able to activate check boxes or radio buttons with the spacebar.

Once selected by a tab key, be able to expand, scroll and shrink list boxes.

I'm not sure how you would handle the slider bars, but it seems to me that once selected with a tab key, that arrows would make the final setting.

The change system fonts and colors popups I expect would be a bit too complex to write shortcuts for, but for the rest, it seems doable, at least for a first try.

I rather expect that you would probably use shortcuts that more exactly conform to Windows standards than my made up ones.