GMT dropdown autoselect according to local GMT?

[eluser]Tyler Diaz[/eluser]
If the topic title did not explain itself too clearly, what I want to do is: Take the date helper GMT dropdown and make it auto select the GMT that corresponds to what may seem as the default one. For example, my GMT is GMT-5. How could I make the dropdown be default selected at GMT-5?

I tried experimenting and searching but did not have much luck. Thanks in advance, Tyler Diaz.