You don't have to buy treasury bills straight from the treasury. Buy them from Schwab and other brokers to spare yourself that ugly website.
You can paste the pw into the field if you edit the html!
This is my method. A little edit and I don’t need to use that dumb keyboard.
There are autohotkey-style scripts for every OS that emulate a keyboard for paste, which can be mapped to a variation of the keyboard shortcut for paste. Very fast to install and you never have to edit html again for this purpose.