How to add an xmlrpc call to take the output of wordpress plugin

Dear pals,
I am using wp 3.6 -oscar . I need a mechanism to call the content of a wordpress plugin for eg : WPBI Lite plugin to another external site.
I refer the post in stackoverflow Is it possible to extend WordPress XMLRPC interface from a plugin?

But still I got the response as “XML-RPC server accepts POST requests only.” Please advise a method to access plugin data to outside world.

Thanks,
Anes