Manipulating the follwoing code should work for you, or at least get you started.

use strict;
use warnings;
my @PS_CMD=`ps -e`;
my @badpid;
my $count=0;

$|++; 

for $_ (@PS_CMD)
{
   chomp;

   ## get rid of trash ##
   next if /<defunct>/;
   s/^\s+//g;
   s/\s/,/g;
   s/,$//g;
   s/^,//g;
   s/(,)+/,/g;
   s/\s//g;
   next unless /^\d+/;
   ## End of trash collection ##

   my ($pid, $tty, $time, $cmd)
     = split(/,/, $_);
   my ($min, $sec)
     = split(/:/, $time);
   # change the $min > ## to change the
   # threshold at which we will be warned
   # change $cmd eq "<COMMAND>" to change
   # the command we "grep" for. Check the
   # output of `ps -e` for an example.
   if ( $cmd eq "YOUR_COMMAND" and $min > 200 )
   {
     $count++;
     push (@badpid, $pid);
   }
}
my $pids=join(', ', @badpid);

if ( $count > 0 ) { send_mail($pids) }
[download]

I left off the send_mail sub...