In the last picture, I think you can use the slot in the chrome retaining ring. I'm not saying that's OEM correct but believe it works. Those ring are somewhat 'flimsy' but I think strong enough to retain the spring. Kind of a PITA to change a bulb as you need to remove the spring to remove the light.
On my car someone improvised and drilled a hole in the bucket, it works and eliminated the need to remove the spring for servicing the light.
http://photos.smugmug.com/photos/i-R...RhNNzcX-X2.jpg