Just a thought, but could you not convert the date/time information for both locations to GMT then convert back to the other? Since GMT is not influenced by daylight savings time, and the timezone information you are using for both locales would likely handle the local influence of GMT, it might be a way to resolve the issue.

Just a thought, though-perhaps someone else can develop the thought, or suggest a better alternative.

Update: After reading your response, I thought about the use of Date::Manip, but noted that it mentioned concerns in dealing with daylight and standard time conversions. However, you can find when the time changes, according to the details located at http://webexhibits.org/daylightsaving/b.html. According to it, daylight savings time begins on the first Sunday of April, and ends on the last Sunday of October. Hope this information might help out.