Something like this (totally untested) code might work for you assuming that the progress reporting on teh remote computer is output to either stdout or stderr:

use threads;

my $fh;
my $pid;
async {
    $pid = open $fh, 
        "scp dvader@empire.gov:file1.txt dvader@deathstar.com:somedir 
+2>&1 |" 
        or die $!;
}->detach;

while( <$fh> ) {
    print;
}
close $fh;
kill 'quit', $pid;
[download]

This runs the command asynchronously through a forking open, redirects all the output to a pipe and then displays the output on the screen.

Note: I've never used scp, so the syntax and indeed the whole idea is just speculation.