On a related note, you may (or may not) be aware that you can program discretes into your MX500 using a device called
IRClone. This is a third-party USB device (and software) that allows you to use your PC to program your MX500. Of most interest to you is the fact that there is software to convert most Philips Pronto infra-red codes for use with the MX500. There are lots of Arcam DV88 and Sky Digital Pronto configuration files on
Remote Central that you could use.
The downside is that you will have to buy the IRClone device as an extra accessory for your MX500. Of course, you could find someone that had a Philips Pronto (or other programmable universal remote that supports discretes like the various All-In-Ones) and use them to learn from directly - that may be a cheaper option.
Hope that helps.