You can probably do that with Crescendo (which I haven't tried in K-Meleon)
<a href="
http://www.liveupdate.com">http://www.liveupdate.com</a>
or, I think, with QuickTime as well... I don't have it presently but in so far as I can remember, QT played midi in K-M.
I think that Media Player plugin does not play midi.