You don't seem to know what you're looking for. At the very least, it wasn't clearly communicated. Please clarify.

Update: Maybe it's one of these:

Override a global package variable for a static scope:

our $var = 'a';
{ my $var = 'x'; print "$var\n"; }  # x
print "$var\n";                     # a
[download]

my $var = 'a';
{ my $var = 'x'; print "$var\n"; }  # x
print "$var\n";                     # a
[download]

Override a global package variable for a dynamic scope: (Doesn't remove magic. Doesn't localise pos() except maybe on recent Perls.)

our $var = 'a';
sub f { print "$var\n"; }
{ local $var = 'x'; f(); }  # x
print "$var\n";             # a
[download]

Override a global package variable for a dynamic scope:

our $var = 'a';
sub f { print "$var\n"; }
{ local *var; *var = 'x'; f(); }  # x
print "$var\n";                   # a
[download]

Override a global lexical variable for a dynamic scope:

my $var = 'a';
sub f { print "$var\n"; }
{ ?????; $var = 'x'; f(); }  # x
print "$var\n";              # a
[download]