Then i would say you'll probably need to do it via API, but the publish api is pretty easy, just make sure though that you add some form of a security key or something for the approval URL so it can't be hijacked (at minimum use the GUID instead of the ID, like /CMSPages/Custom/ApprovePage.aspx?gid=abcde-feafd-afeafe-32f3 so no one can just randomly guess it)