vista theme distributed

Hello,

Is there a way to distribute theme to enterprise systems after the build
process?

For example, I do not want to use the unattend.xml file, but I would rather
distribute the theme as a SMS package.
The requirement is that the theme can be changed by the user; therefore,
group policy can not be used this time. Group policy would not allow the
user to modify the theme.
Also, the theme must be the default theme for any logged on user after the
theme is distributed.

The theme is very simple at this point: a company wallpaper and transparent
sidebar.

Thanks for any help.

Regards,