Display notices on APM logon Page dynamically

One method you could use would include ACCESS_POLICY_AGENT_EVENT event. You could create a macro (Link 1, Link2) within the VPE, that contains a iRule event, and a Message box (APM page with a message) if a certain variable is set. Then the VPE can continue as normal, and all you'll need to do to enable the page is set the variable in the iRule.

What I'm not entirely sure of since I've never tested is whether you'll need to use a session variable to enable the page, or if a GLOBAL variable will work.