Shortly after I published the original article, I found a bug in the fglrx installer in 12.04.5 and 14.04.2 with the new Hardware Enablement Stack.

If this has affected you, you are in luck if you use Trusty.  The fix has been applied to the trusty-proposed repo -- and may even have made it to the main trusty repo.

If not, please have a look at post #77 in the bug here for how to install it from the -proposed repo.