properly take quantifiers into account (cf. my Ph.D. thesis, Section 6.4.1) and offer three modes of completeness (for experiments mostly)
#! /bin/sh
#
#sedindex - shell script to create indexes, preprocessing LaTeX's .idx file
#
# puts strings prefixed by * into \tt font
# terminator characters for strings are |!@{}
#
# a space terminates the \tt part to allow \index{*notE theorem}, etc.
#
# note that makeindex uses a dboule quote (") to delimit special characters.
#
# change *"X"Y"Z"W to "X"Y"Z"W@{\tt "X"Y"Z"W}
# change *"X"Y"Z to "X"Y"Z@{\tt "X"Y"Z}
# change *"X"Y to "X"Y@{\tt "X"Y}
# change *"X to "X@{\tt "X}
# change *IDENT to IDENT@{\tt IDENT}
# where IDENT is any string not containing | ! or @
# FOUR backslashes: to escape the shell AND sed
sed -e "s~\*\(\".\".\".\".\)~\1@\\\\isa {\1}~g
s~\*\(\".\".\".\)~\1@\\\\isa {\1}~g
s~\*\(\".\".\)~\1@\\\\isa {\1}~g
s~\*\(\".\)~\1@\\\\isa {\1}~g
s~\*\([^ |!@{}][^ |!@{}]*\)~\1@\\\\isa {\1}~g" $1.idx | makeindex -c -q -o $1.ind