try to get the ip of your server and check the ip with some service, which will tell you from which country it is and search for that specific country timezone.. I don't know if it works as you want, but it is an alternative.. and could be incorrect, for example if the ip will be EU Europe Union..
Err, can't you do it with some server side scripting language?
I've seen similar question on Xistosupport site. You can take a look at it here. To make it short, let me sum it up this way. As per that answer, computinghost servers are located in California. So as per pacific timezone, California is GMT-8hrs. For DST timings, it's GMT-7hrs. Hope this helps.
