Thanks for the responses.
This is an email i sent to someone who asked about the unit.
Ok this aint the easiest project ive ever done but you need to get the transmitter and receiver kit from here [Link: rentron.com]
the transmitter circuit can be modified to be simply than what the diagram shows at the URL above. Basically you need the IR Reciever (its the TSOP-1140), the 2.2k resistor from the OUT of the IR Reciever needs to be 1.2k (at the most, in fact thats what im using but i think ill need to drop the value to 800R or 1k) to the base of the transistor, and the actual transmitter circuit with antenna. NOW the TSOP-1140 is a 5v IR reciever that you get with the kit and is no good because most PDAs run on 3.3v, i swapped this component for the TSOP-34838 (you can use the TSOP-34840) which will work at 3.3v.
Now thats the transmitter part, i put this into the SD Card slot of my PDA (it just fitted and theres plent of room above the SD slot and even then its pretty tight so i dont know if it'll work on all PDAs). The IR Reciever, thats the TSOP-34838 needs to go either in front of you IR port on the PDA OR (like i did) but a bit of tin foil over the IR port (inside the PDA) and sat the IR Reciever behind it and glued it in position (this is internally of the PDA). So when the PDA transmits out of the IR port, it reflexs and back into the IR Reciever of the transmitter.
The actual RF to IR Receiver of this project (as shown in the URL) ive left as it is and works fine. There is however a problem. The Transmitter of the circuit (in your PDA) needs the antenna outside of the PDA as its shielded and no RF signal gets through it. Also when the RF - IR circuit recieves a signal it is depentant on the signal strength to how well it works so the closer the transmitter (PDA that is) the better it actually works. Now im working on the RF - IR receiver to be better with a buffer before it actually sends the IR signal to the cinema unit sets so the signal strength is always very strong but yet to do that.
If you would like (it'll take me a few days to do) i can do a circuit diagram of what ive used from the URL and couple pictures of the setup (including inside my PDA where the circuit is).