Special Characters In GNOME/KDE Login Password
 

It is my understanding that Linux does not allow to enter ASCII codes by pressing the ALT key + 3-digit code (using the keypad) as Microsoft Windows does.

I am using a standard QWERTY keyboard available in the USA.

So, if I wanted to create a GNOME or KDE login password full of special characters such as this one: ...how would I do that?

I would not consider most of the characters you have presented as ASCII, but rather unicode. Try searching for integrating unicode into your login.