%subs = (
    foo => sub {
        print "Hello, world!\n";
    }
);

sub AUTOLOAD {
    ...
    *$AUTOLOAD = $subs{$name};
    ...
}

##</code><code>##

%subs = (
    foo => 'print "Hello, world!\n";'
);

sub AUTOLOAD {
    ...
    *$AUTOLOAD = eval "sub { $subs{$name} }"
    ...
}