To create a cPanel account please first log in to WHM (Web Host Manager).
Once there select "Account Funtions" > "Create a new account"
Simply all you should need to do here is fill the form with the Domain name, and username and password you want for the account.
Then make sure to select a package type, (which you should have already created by this point if not please view the related article "Creating cPanel Packages" ) and the select the Mail Routing Settings:
Please make sure to read through the descriptions and make sure you choose the solution that works best for you. If you need help setting up Custom MX records for your remote mail server please submit a ticket with the MX records you would like changed at support@midphase.com.