Comment 22 for bug 429003

I guess my question, "...is there a way to block that?" should have been, "How do I pin the older libraries?" I did a search and found this:
Edit /etc/apt/preferences with something like this:
   1. Package: ruby
   2. Pin: release a=hardy
   3. Pin-Priority: 900

Is that what needs to be done? If so, is this what goes in the lines?
   1. Package: eglibc
   2. Pin: release a=jaunty
   3. Pin-Priority: 900
Or something else?