Do what they did in Tivoli verification.  Go to SMIT, change the system
date and time to December 31, 1999,  and pick a time, say about 23:30, and
reboot the box.  Once you have your system back up, watch what happens when
it rolls over.    Think about everything you have running when it does
this, netmon, snmpCollect, rulesets, GUIs,whatvere, and then go check that
it is still running and working OK.   Do this many times until you are
satisfied.
Have fun.

James Shanks
Tivoli (NetView for UNIX) L3 Support