I never thought of tieing the variable... this is how I use IO::Scalar when I wish to redirect output.
It's actually more useful for when you just need to have output to a variable rather than to some file handle:

use IO::Scalar;
my ( $STD1 $STD2 );
$STD1 = new IO::Scalar \$STD2;
select $STD1;

print <<DONE;
blah blah blah
All this is being appended to the $STD2 variable
So some more text here and we are...
DONE

open FILE, ">test.txt";
print FILE $STD2;
close FILE;
[download]

Yes, odd example since you could have just used:

open FILE, ">test.txt";
select FILE;

print <<DONE;
all that stuff again. I am
DONE
[download]

But you get the point...