If you're willing to stick with backspace and carriage return, this really isn't a hard hack at all. Here's a twirly-bob:

{
        my $p=0;
        $|=1;
        sub tick {
                print substr(qq{|/-\\|/-\\}, $p++, 1), "\b";
                $p=0 if ($p > 8);
        }
}
[download]

Just call tick repeatedly and the thing will spin. Or a percentage meter:

{
        my $bar=qq{0%..........50%..........100%};
        $|=1;
        sub bar {
                local $_=$bar;

                substr($_, $_[0]/100*length($_), 1)="|";
                print "$_\r";
        }
}
[download]

Just call bar with a number between 1 and 100 to indicate how complete things are.