Here is a quick way to set a timezone:

A list of timezones for php: http://www.theprojects.org/dev/zone.txt

To get the timezones into a file quickly:

wget http://www.theprojects.org/dev/zone.txt

cat zone.txt | awk ‘{ print $3}’ >> timezones.txt

Remove the first few lines and you have an easily read file that you can make a selection box out of.