There is actually a TSB issued on setting it but check pg 2-22 Instruments and controls in the owners manual. Here is the info from the TSB...
370Z COUPE AND 370Z ROADSTER; TRIPLE METER CLOCK SETTING PROCEDURE
APPLIED VEHICLES: 2009-2010 370Z Coupe 2010 370Z Roadster
Classification: Reference: Date: EL09-039 NTB09-109 October7, 2009
SERVICE INFORMATION
If the clock (located in the Triple Meter, above center in the instrument panel) needs to be set, use the procedure starting on Page 2.
Nissan Bulletins are intended for use by qualified technicians, not 'do-it-yourselfers'. Qualified technicians are properly trained individuals who have the equipment, tools, safety instruction, and know-how to do a job properly and safely. NOTE: If you believe that a described condition may apply to a particular vehicle, DO NOT assume that it does. See your Nissan dealer to determine if this applies to your vehicle.
3
Combimeter
NOTE: Refer to Figure 1 on Page 1 for component location.
1. Turn the ignition on.
2. Press the Enter switch repeatedly until “Setting” shows in the upper right of the Vehicle Information Display.
3. Press the Next switch repeatedly until “Clock” is highlighted.
4. Press the Enter switch once.
5. Press the Next switch repeatedly until “Setting” is highlighted.
6. Press the Next switch repeatedly until the desired hour value is reached.
7. Press the Enter switch once.
8. Press the Next switch repeatedly until the desired minute value is reached.
9. Press the Enter switch once.
10. Press the Next switch repeatedly until “Back” is highlighted.
11. Press the Enter switch repeatedly until out of the setting mode.