[Ed Zachary]

I was hoping to find an answer to this, as well.
Using the Settings tab tells TouchFlo to use something besides the default wallpaper for the Home tab only. The other tabs continue to use the default.
The default wallpaper is in a _manila file in the Windows folder.
If someone could figure out WHICH _manila file it is, another pic could be used and manila editor used to create that file. Something like TotalCommander could then be used to replace the _manila file on the phone, and, viola!, a new wallpaper that will be used on all the tabs, not just the home tab.

Yes, there are apps that can be used to customize the backgrounds for all the tabs, but they tend to alter the behavior of other things and are iffy with stock ROMs.