batface - 3:02 pm on Nov 8, 2012 (gmt 0)
I would like to say it works, but it doesn't. I followed your steps and placed the expires htaccess in the image folder.
I am at the same position -
^18.104.22.168 = no alternative image
!^22.214.171.124 = always alternative image
I also purge the cache with Fiddler in case.
It is a fixed IP.