Hi,
There is no way to do so through Ajax call, because when an Ajax call is made for Cross Domain the method type "OPTIONS" is passed to the server and Kibana does not have a way to handle OPTIONS call in there product built code. They gave an option of using proxy server where you can authenticate and pass the request forward, but that still did not work for me as iframe cannot be shared in CROSS Domain.
Hope that suffice what you wanted.
Regards
Tushar