Today I installed Xcode on my Snow Leopard and decided to play around with it.
For testing, I used a Mac OS X file archiver called Keka [link]
I managed to change the "Processing Window" and the "Advanced Window" for a HUD interface.
As always, just open and move the ZIP contents to "Keka / Contents / Resources / en.lproj "
Tested on version 1.4.1
In the preferences of the program if you select "Close Keka when no window visible" and try to open a password protected file, a message will appear asking if you really want to close the program and you can not open the file. So whenever you open a password protected file, remember to uncheck the option mentioned above.
I do not know anything about Xcode, InterfaceBuilder and etc ... but I think Keka does not recognize the HUD interface as "windows" but as "panels", so the program always tries to close automatically.
If anyone knows how to fix it, please share.