how about this (a bit like languages and bodyfonts)

\unprotect

\newconstant\c_scripts_injection \c_scripts_injection\attributeunsetvalue
\newconstant\c_scripts_splitting \c_scripts_splitting\attributeunsetvalue
\newconstant\c_scripts_status    \c_scripts_status   \attributeunsetvalue

\unexpanded\def\setglobalscript[#1]%
{\edef\currentscript{#1}%
   \scripts_basics_set
   \c_scripts_injection\attribute\scriptinjectionattribute
   \c_scripts_splitting\attribute\scriptsplittingattribute
   \c_scripts_status   \attribute\scriptstatusattribute}

\unexpanded\def\setlocalscript[#1]%
{\edef\currentscript{#1}%
   \scripts_basics_set}

\let\setscript\setlocalscript

\appendtoks
   \attribute\scriptinjectionattribute\c_scripts_injection
   \attribute\scriptsplittingattribute\c_scripts_splitting
   \attribute\scriptstatusattribute   \c_scripts_status
\to \everypagebody

\protect