all timezone information is stored at /usr/share/zoneinfo you can browse to this by typing
you should see a list of all the available timezones including folders for countries which have multiple time zones eg. America
so to change the time zone just enter the following
ln -sf /usr/share/zoneinfo/Europe/London /etc/localtime
If you then want to manually set the time to 30/03/2008 09:57, the format to enter the date is 'mmddhhmmyyyy'
The following command will update your hardware clock
And now when you type in 'date' you should see an up to date clock