I recently picked up a couple ProCurve 2910al-48G-PoE switches. Since it had been a while since is setup time on a switch I had to research a bit. Here are the settings I used.
First, you can view the switches current time, timezone, etc. with the show time command.
Next go into config mode (configure terminal) on the switch’s CLI.
sntp unicast
sntp 30
sntp server priority 1 65.55.21.17
sntp server priority 2 64.250.177.145
timesync sntp
time timezone -300
time daylight-time-rule continental-us-and-canada
Now, when I run show time the switch displays the current local time!