"All I want to do is ..."

To be honest, that's not quite as easy as your pseudo-code implies.

if (my $pid = fork())
{
  # parent
  monitor($pid);
}
elsif (defined $pid)
{
  # child
  exec(@command);
}
else # fork failed.
{
  # How do you want to handle this?
}
[download]

Of course, monitor is the tough part. You'll probably need to set a signal handler for SIGCHLD - so you'll know when the child exits. You'll want to probably use Term::ReadKey, although I'm not sure if ReadKey will return if interrupted with a signal. And then, if you do get the right key, you can use kill to kill the $pid we got from fork.

I hope this helps, barring some more adventerous monk writing a more complete example.