prboom - Timidity patch

Hello,
I just installed prboom on my Win XP computer, and it works fine. The
only thing that is not working is MIDI sound. I tried using the
provided SDL_mixer_beta.dll, which works but does not loop.

Obviously, this is a known bug.

I have read a lot about the advice to use timidity patch instead. I
have no idea what this means or how to do it. Can somebody provide me
with some more detailed instructions on what to download (and possibly
from where), and what then to do with it? Just install on the PC? Or
onto prboom? I really have no idea...

Thank you!
Alex