Hmm..........

{
$foo::bar = "Show me";
print \*{"foo::bar"};
local %foo:: = %foo::;
print \*{"foo::bar"};
print ${"foo::bar"};   # runtime lookup
}
[download]

Looks like that's enough. Your big problem is that even changing the glob addresses has no effect in the rest of the program, since perl never looks up symbol-table entries at runtime unless you use a symbolic ref. There is very limited functionality to replacing the glob entries in the symbol-table, since you must use it like a hash in order to see the effect.