Colin,
First of all, if you have to write to protected Windows areas (e.g. the "Program Files" folder tree or HKEY_LOCAL_MACHINE registry) then your update has to run elevated. Otherwise, the update does not have any write access. If you only write to "un-protected" areas, then you can run the update non-elevated. But in this case, you have to compile and include your own version of wucheck.exe (\Redist\1033\wucheck.sbp) -- just uncheck the "Run elevated from non-elevated SetupBuilder application" option in Line 219 and 221 and you are done.
Does this help?
Friedrich