You must use superuser privileges to set the date but it is not necessary to enable root.
Example
sudo date mmddhhnnyyyy
... but you must substitute the actual date and time in the command that corresponds to the date format used for your location. In other words if your custom is to use a date like 8 February 2014 then reverse the mm and dd values.
Substitute numerals in the above command according to the following:
mm = month
dd = date
hh = hour (24 hour format)
nn = minutes past the hour
yyyy = year
Each of those values must be two digits except for the year which can be two or four digits. As an example if the current date and time is February 8, 2014 at 9 PM your command will be the following:
sudo date 020821002014
or
sudo date 0208210014
Either one will work. If you enter nonsensical values the system will attempt to parse the entry correctly.
Terminal will ask for your Admin Password - the same one you use when you log in to your Mac. Type it and then press the Return key. What you type will not appear, not even with •••• characters.
To verify that your change was effective just type the date command and press the Return key. Terminal will reply with the date and time. The value entered does not have to be precise, it just has to be approximate. Selecting the "Set time and date automatically" checkbox and choosing an appropriate time server in System Preferences > Date & Time will adjust your Mac's system clock to the precise time.