I have build such a device which used a Phillips 87C750 and decoded RC-5 IR signals. It was based on code which was taken from the Phillips Web Site. If you want a copy of my code then please e-mail me and I will send it to you. The 87C750 is very similar to the atmel 89C1051 and should need no modification to the design for it to work. Mine just decoded 6 RC-5 codes but the code is very easy to adapt to any RC-5 code and number of outputs (limited only by your choice of MCU ).