http://www.petri.co.il/disable_uac_in_windows_vista.htmMethod 2 should do fine... Make 2 reg files and run one before WPI then reboot. Add the second one (Re-enabling UAC) to WPI's execute after.
As for elevated abilities you need to do that on a file for file basis.
Study this cmd file here:
CODE
takeown /f %systemroot%\System32\uxtheme.dll
icacls %systemroot%\System32\uxtheme.dll /grant administrators:F
ren %systemroot%\System32\uxtheme.dll uxtheme.old
xcopy /y %systemroot%\System32\Patches\uxtheme.dll "%systemroot%\System32\"
takeown /f %systemroot%\System32\themeui.dll
icacls %systemroot%\System32\themeui.dll /grant administrators:F
ren %systemroot%\System32\themeui.dll themeui.old
xcopy /y %systemroot%\System32\Patches\themeui.dll "%systemroot%\System32\"
takeown /f %systemroot%\System32\shsvcs.dll
icacls %systemroot%\System32\shsvcs.dll /grant administrators:F
ren %systemroot%\System32\shsvcs.dll shsvcs.old
xcopy /y %systemroot%\System32\Patches\shsvcs.dll "%systemroot%\System32\"
I use this to replace the uxtheme files.
You would need to use similiar methods to copy\modify files with WPI
(Please keep in mind though I only adopted Vista AFTER SP1 was released) I had beta tested it and tested it for a little while when it was first released and found that I greatly disliked it.

Now though it's not so bad....
I am pretty sure there is better ways but I don't know them.