Get my PKG Installer To Prompt and Store Admin User/Pass
From this documentation...

http://s.sudre.free.fr/Software/documentation/Packages/en/Package_Settings_Customization.html#6

...it states that Apple PackageManager files (.PKG) files have an option to run with Administrator privileges. It specifically states:


  If you install anything in /Applications or /Library, this option
  should be enabled.


Also, in this documentation...

http://s.sudre.free.fr/Stuff/PackageMaker_Howto.html

...it states that Bash scripts that you run will run under Administrator privileges (root) and therefore will not require sudo authentication to do powerful tasks.