Edit APM logon Page

In the management GUI:

1. Access Policy -> Customization -> Advanced

2. Select "Advanced" from the Edit Mode option list

3. Drill down to your specific logon page:

   Customization Settings
   Access Profiles
       [Your access profile]
           Access Policy
               Logon Pages
                   Logon Page
                       logon.inc
   

Here you'll see the bulk of the HTML used in the logon page. Edit this file, click the "Save Draft" button and then the "Save" button. Apply the access policy and test.

Also review this guide:

http://support.f5.com/kb/en-us/products/big-ip_apm/manuals/product/apm-customization-11-2-0.html