There are several files for Sony receivers in the MX-500 file section here at R/C, maybe one of them has the DSP buttons programmed.

The problem with the DSP commands is that it's very hard to get most universals to learn the signal because it's so long and it repeats, so they don't know where it starts and stops.

If all else fails, I could program a One For All remote with the DSP commands, in such a way that they won't repeat, so you could use the OFA remote to teach them to your MX-500.

It's unlikely that you will be able to scroll through them though. The original Sony remote has an LCD screen where you scroll through them, then when you select one, it sends it as a discrete code.