Tell IIS to ignore Accept header?

I found one browser (Obigo) that sends an Accept header that does not
include "text/html". It only does this when using SSL. Obviously
something wrong with the browser, since it does support text/html.
I'm guessing if IIS went ahead and returned text/html the browser
would be fine, but currently IIS returns a 406 response.

Can I force IIS to ignore the Accept header?

I do have an ISAPI filter, so maybe I can use that to modify the
Accept header? Would that just be "SetHeader" in the pre-process
headers notification? I'm thinking maybe I'll just set the Accept
header to */*, all the time... or maybe only if User-Agent contains
"Obigo".