What is your setup, do you have a B&O tv or do you plan to control it directly ?
I have written a small how-to here
http://www.rungwald.dk/Beo4-5_MCE_Control/
I myself control MCE via the MCE original IR reciver and the STB-Controller of my Beosystem 3, and have just add'ed pages and buttons to the Beo5 that sends the codes i have mapped.
That is, i am using this http://www.rungwald.dk/Beo4-5_MCE_Control/stb.html
Please tell me more about your setup before i can guide you in what you should do.
/Weebyx