Why can you not do the relatively simple ?

    $cmd="myCommand";
    # Timeout evaluation:
    eval {
      # Set action to be done when alarm occurs:
      local $SIG{ALRM} = sub { die "ALARM_COMMAND_TIMEOUT" };
      # Schedule alarm in $CMD_TIMEOUT seconds:
      alarm($CMD_TIMEOUT);

      ### execute the command that can block
      $Results = `$cmd`;
      if ($?) {# optional error handling}
      }
      wait;
      alarm(0);

      close(PIPE);
    };
    alarm(0);
[download]

The backticks spawn a child to run the command and block 'till it returns

Update

OK, I tried that, well this perl -le'$SIG{ALRM}=sub{die "TIMEOUT"};eval{alarm 1;`sleep 100`};print $@' and it did not work for me, this did however

perl -le'$SIG{ALRM}=sub {die "TIMEOUT"};
     eval{alarm 10;
          open PIPE, "while [ 1 ] ;do echo \"foo\";sleep 5;done|";
          while (<PIPE>){print}};
     print $@'
[download]

If you trust the child to die on SIGPIPE then it will die when the eval exits

Cheers,
R.