use AnyEvent;
use AnyEvent::Util;
use File::Spec;

my ($stdout, $stderr) = ('', ''); # I think these need to be empty strings, not undefs
my $pid;

my $cv = AnyEvent::Util::run_cmd [ qw(xcopy /Y /S /E /I /F /R /K), $source, $dest ],
  '<'  => File::Spec->devnull(),
  '>'  => \$stdout,
  '2>' => \$stderr,
  '$$' => \$pid, # this line is optional, you may not need it.
  ;

my $rc = $cv->recv();