Use strstr to find the '-', then use substr to extract the parts you want and build a new string.
Note: since strstr will only find the first occurance of '-', you'll have to cut that part out once your done with it. Such as:
$date = "05-04-2002";
use strstr to find -, then use substr to assign $month = 05
now $date = $date - the "05-" part.
Repeat process for day, and year.