How to add cross domain support to WCF service

I’m trying to allow POST requests from my javascript app hosted at localhost:80 to a WCF REStful service hosted at a different port, but somehow it doesn’t work. I’ve tried adding custom properties to the header, as well as adding it programatically in my service’s JSONData method but I’m still getting ‘405 Method not allowed’ in my response. What is the proper approach here ?

Check ssl protocol, cipher & other properties in an asp.net mvc 4 application

Because of compliance reasons we have to switch off the support of some ciphers and SSL2 on our webservers. This is not really a problem, but we would also like to inform them, after their successful login into the website, that we suggest switching on TLS 1.2 in their browser in case they are not already connecting to the server with TLS 1.2. So the question I have is: