I wasted several days trying to use the old Address Book package (for
a client site) on ACS 4.2 back in 2001, and as I've described
elsewhere in the forums, my evaluation at the time was that it was
roughly 85% worthless junk. I had many more details then but that was
the bottom line. Most people who looked into it independently seemed
to reach similar conclusions, thus, I'd bet that little or no work at
all has been put into the Address Book code since the original
maintainers at aD orphaned it in early 2001.