Two ways to do this:
Use local Certificate Authority (CA) in your environment which is acting as a Root CA:
You can use that Root CA to create a subordinate CA certificate. In this case, you would need to push the Root CA certificate to your clients. For Windows systems, you could push via GPO to the Windows certificate store and that will handle Internet Explorer, Chrome, and Opera. For Firefox, the certificate will need to be imported to the browser.
Use self-signed certificate generated on MWG:
Then distribute that cert to client machines and install it in the Trusted Root Certificate store (or for Firefox, in Certificate Manager, Authorities).