HowTo: Setup EWW To Handle mp3 urls

[raman]

I'd like to hand off content-type 
audio/x-mpegurl and friends to mplayer --- preferably to an elisp
function I write to handle these via mplayer.

How/Where do I set this up to tell eww to hand me those content-types?

/etc/mailcap maps media type audio/x-mpegurl to totem, but when I
follow those links in EWW, it hands them off to Mozilla by default.
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