Send bit to specific parallel port pins with php

Question

I need to send a bit (pulse) to specific pins of a parallel port to control some stepper motors...

With the php_serial.class.php class I know how to send a string, but how to send only one bit and specifically to a port? Would it be possible?

$serial->deviceSet("COM6");
$serial->confBaudRate(9600);
$serial->confStopBits(1);
$serial->confCharacterLength(8);

$serial->deviceOpen();

$serial->sendMessage("\xFF\x01\x01");

$serial->deviceClose();