Unfortunately I'm unfamiliar with what you're trying to achieve. Are you're using Apache to authenticate or to proxy your server which responds to SOAP?
If not, you're probably doing some sort of request (e.g. cURL, PHP HTTP request, etc.), which don't depend on Apache, as it is only the frontend server incoming requests.
If you're using Apache as a proxy server to your server which uses SOAP, you might consider proxying to HTTP and not HTTPS, if both servers are in the same network and safe from man-in-the-middle attacks.
In the end, the user would connect to your Apache server via HTTPS, and its connection would be secure, so encrypting that part of the network might not make much sense.
If you're still having troubles, we would appreciate if you could explain in a bit more details what you're trying to do, and how, as we're still a bit unsure about what you're trying to do.