Create a Warning message box in APM policy before Logon Page

Well, the info displayed in the decision box is displayed as is, on the left column. I wouldn't know if you could have it show up in the center of the page. Check Access Policy --> Customizations for a list of preferences you could customize to your taste on the APM. And, I don't think you can publish anything separately to show up on the page in the course of execution of the access policy. it has to be within the Start --- End (Deny/Allow) line in the VPE