[CentOS] Gradually adjust NTP sync over time?

Tue Sep 4 16:17:59 UTC 2012
Sean Carolan <scarolan at gmail.com>

Suppose you have server A and server B.  Server B is running 60
seconds too fast, while server A is accurate.  Is there a way to
gradually move server B's time back into sync with server A, without
making a drastic, immediate change to the clock?  In other words, we
would like to 'smear' the difference across several hours or days to
ensure there are no drastic changes in timestamps, etc.