Macos – How to you lock start the screen-saver in OS X with a keyboard shortcut

Just remove keyboard and mouse altogether and manage the Mac remotely with VNC.

EDIT to remove USB support: You can remove USB support in Terminal with the following commands:

cd /System/Library/Extensions 

TO BE SAFE do this code first:

sudo cp -r IOUSBFamily.kext /Users/<youraccount>/Desktop

Then

sudo rm -r IOUSBFamily.kext

Reboot and USB support is gone. Be sure you have a good VNC or ssh connection first so you can put that .kext file back when you want to be able to use the USB ports again.

It appears that this program should be able to do what you need for other WIN key combinations since WIN-L and WIN-U seem to be hard-coded into the OS (your questions serves as a perfect example of why hard-coding stuff like this is generally frowned upon in many software development communities):

  Auto Hotkey (free and open source)
  http://www.autohotkey.com/

This web page specifically mentions the WIN-L and WIN-R hotkey combinations:

  Overriding or Disabling Hotkeys
  http://www.autohotkey.com/docs/misc/Override.htm

• "You can disable all built-in Windows hotkeys except WIN+L and WIN+U by making the following change to the registry ..."

It's too bad that this can't be the exact solution you're after, but perhaps it will at least be somewhat helpful. If you don't mind using a different WIN hotkey combination to logout, then hopefully this solution will be what you need.