BIG-IP APM - Customized Logon Page

@Kevin - could you post some more detailed info how to implement this in logon.inc - I tried to paste code like that:

function dropdown(){
  var allTDs = document.getElementsByTagName('td');
  for(i=0; i < allTDs.length; i++) {
    if(allTDs[i].innerHTML.indexOf('appname') > 0 && allTDs[i].innerHTML.indexOf('auth_form') == -1) {
      var replacetext = 'Application%{session.custom.logon_opt}';
      allTDs[i].innerHTML = replacetext;
    }
  }
};
function OnLoad()

as well as

function OnLoad()
{
function dropdown(){
  var allTDs = document.getElementsByTagName('td');
  for(i=0; i < allTDs.length; i++) {
    if(allTDs[i].innerHTML.indexOf('appname') > 0 && allTDs[i].innerHTML.indexOf('auth_form') == -1) {
      var replacetext = 'Application%{session.custom.logon_opt}';
      allTDs[i].innerHTML = replacetext;
    }
  }
}

but nothing happens on the logon page, just text field is displayed as defined in Logon Page. I can see that modified code is send to client so that is not the reason.

Thanks in advance, Piotr