Q:\>perl -v

This is perl, v5.6.1 built for MSWin32-x86-multi-thread
(with 1 registered patch, see perl -V for more detail)
(snip-snap)

Q:\>perl -e "$foo='bar'; use lib $foo; die join ';',@INC"
Empty compile time value given to use lib at -e line 1
;s:/Os/OSP/OSPI/Perl/lib;s:/Os/OSP/OSPI/Perl/site/lib;. at -e line 1.

Q:\>perl -e "BEGIN{$foo='bar'; use lib $foo;} die join ';',@INC"
Empty compile time value given to use lib at -e line 1
;s:/Os/OSP/OSPI/Perl/lib;s:/Os/OSP/OSPI/Perl/site/lib;. at -e line 1.

Q:\>perl -e "BEGIN{$foo='bar';} use lib $foo; die join ';',@INC"
bar;s:/Os/OSP/OSPI/Perl/lib;s:/Os/OSP/OSPI/Perl/site/lib;. at -e line 1.

Q:\>perl -e "BEGIN{my $foo='bar'; eval qq{use lib $foo;}};die join ':',@INC"
bar:s:/Os/OSP/OSPI/Perl/lib:s:/Os/OSP/OSPI/Perl/site/lib:. at -e line 1.