Nevermind. I figured it out...
$start_week_day=mcal_day_of_week(2006,1,1);
$num=(6-$start_week_day)+1;
What this does is finds what day of the week 1/1 is. It then takes 6 (which is the number for saturday) and subtracts the day of week that 1/1 falls on and adds 1 (to compensate for 1/1).
Thanks,
-Andrew