The code below can be used to execute code during certain days of the week.
So, once a day, you would send a cron to wherever this code is located and it will only execute on Mondays - Fridays.
//we only want to send this on monday-Friday.
$day_name = date('D');
//execute this script weekdays only
if($day_name == "Sat" || $day_name == "Sun") {
echo "error - this script can only run mondays to friday. Today is $day_name.";
exit;
}