Just saying in this in case it will help you. For treasurydirect, you can use inspect element and change the value="" field on the password element, and paste in your password from your password manager. It's not as convenient as autofill from your password manager, but it sure beats using the graphical keyboard.
Thanks! That would definitely be a way to do it. I was hinting at something similar by saying "unless you use a user script to make the field editable again". You could also run a bookmarklet that makes the input editable using JavaScript, and then using the password manager. But it's a pain in any case if you're using the site on a mobile device.
