Is there a way to set "Use a proxy server" to "On" in Proxy settings using the command prompt?

Question

I know how to set my proxy server using the command prompt, this is a simple case of typing: netsh winhttp set proxy http://myproxy.mydomain.co.uk:8080

The problem is that I not only want to SET my proxy server, but I want to ENABLE it too. Does anyone know if this is possible as I have trawled the net for over an hour now to no avail.