Manually Changing Login Screen Halp?

So, before the login screen was a simple login.swf file we could just swap and then change the music in a similar manner by replacing the .mp3.

With the new, more complicated login screens (like DJ Sona's) how would I manually change it? Does anyone know?

Putting it simply, I love the current DJ Sona login screen quite a bit and I would want to be able to save it on my desktop to replace later login screens if they end up not being as fun as I like. If anyone could help me figure out how to do that it would be great :)