Sounds like you'll have to do this twice a year! The procedure is pretty simple actually (after you turn on the device!)..
# Tap the bottom tab
# Tap the tool image (setup menu)
# Select the clock image (Time zone and date)
# From here you can edit the highlighted items (Day, Month, Year, Hours, Minutes) by tapping the up or down arrows!
# To apply the new setting, tap the "OK" button
You can even specify your home and travel time zones by following the instructions on page 149 of the [http://cdn-10.nikon-cdn.com/pdf/manuals/kie88335f7869dfuejdl=-cww2/S4100_EN.pdf|user manual]!
Hope that helps!