If you are using X4 either it was recently purchased or you have paid for "maintinence" from "M.C.". So there IS a post. Click on "Machine type", click on "MILL", and scroll down to "Haas mill", and click on it, then you are done.
Find your toolpath and post.
But if your using VQC (a waste of time if you have paid for MasterCam), why are you concerned about a post?