Simple exploding should do the trick:
$monthNamesToInt = array('Jan'=>1,'Feb'=>2, 'Mar'=>3 /*, [...]*/ );
$datetime = '05/Feb/2010:14:00:01';
list($date,$hour,$minute,$second) = explode(':',$datetime);
list($day,$month,$year) = explode('/',$date);
$unixtime = mktime((int)$hour, (int)$minute, (int)$second, $monthNamesToInt[$month], (int)$day, (int)$year);