As you have the data cable, does it plug in the serial port or USB port?, this onviously makes a BIG difference!.
Assuming it's the serial port?, I suggest you write a program on the PC to learn to control it - it gives you a LOT more options, is easier to do, and you know the hardware is already working. Once you have that done you know EXACTLY what you have to send, and it's trivial to port it to the PIC.
Depending on how it works, you may even be able to configure Hyperterminal to do the job, and input the commands manually - again this would show you exactly what the PIC has to do.
Assuming it IS the serial port, you will need a MAX232, or some other type of level changer.
Also why use last centuries obselete PIC?, why not use a current one - like the 16F628 that replaced the 84 years ago!.