Take a glance through the man pages for date.
It's been a couple of years since I last used it,
but when I did, it was for the express purposes
of changing the system date to a specific time.
It was on an old SB100 with an unpatched OBP.
Their system clocks would wander all over the place
until the problem got fixed with an OBP update.
If I recall, the command syntax I used was something like ...
# date HHmm.ss <enter>
For example -- "date 1832.50" would be for 18:32:50 o'clock of the system's current day and timezone.
... then I used the simpler date command syntax to check up on the results.
# date <enter>
Other forum contributors may have their favorite suggestions, as well.
man date.
If this is a live server, pay close attention to the date -a
command. That lets you accelerate or decelerate the date/time to either catch up to the correct date/time, or slow it down to match the current date/time.
Prevents wreaking havoc with the audit logs, etc. As I remember, it shaves or adds 10 seconds per minute until the correct time is reached.