Set cipher suites used by WinHTTP

Question

I would like to use WinHTTP to verify the correctness of some cipher suites which are a modified version of OpenSSL ciphers.

However, I am not able to force WinHTTP to use a specific cipher when contacting a TLS/SSL server. I tried a couple of things, but none worked.

Here is what I tried:

1. Using the CryptoAPI to remove cipher suites: I basically removed all cipher suites and added the one I wanted to test using the API functions: BCryptAddContextFunction() and BCryptRemoveContextFunction(). Here is a link.
2. Followed instructions here to in the section "To configure the SSL Cipher Suite Order group policy setting".

But none of these worked. Is there any clue how to do this?

btw, I am using Windows 7 Enterprise. And I am verifying what ciphers are being used using Wireshark.

Thank you in advance.