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

So I know this post is old, but I have not seen an answer on how to hardcode the domain into the Webtop login. This is how I accomplished it. I would be interested in knowing if others did it differently.

Pull up the visual editor policy you want to work on. Click on the Logon Page action property. When the new box appears, go to the customization section and select the language you want. If you are just using username, password, and domain go to Field 3. Enter in the word "domain". Go back up to type and enter none from the drop down. Under Post Variable Name and Session Variable Name enter the domain name with no slash marks. Save and apply the policy.

Browse to the webtop and you should only see text boxes for username and password. Enter the appropriate names and you should be all set.