How to hardcode/ create dropdown domain list to secure logon page

Will you only ever be using one domain? Or will there be multiple domains that users can log on to and you want them to be able to select from a drop down list?

If it is the former, you could just not display the domain field on the log on page and then use the variable assignment in the visual policy editor to set the domain value using the session variable session.logon.last.domain