I do not think there is a straightforward answer yet. I saw some discussion of this a while back, but I do not recall where. Until 64 bit numbers become available most platforms, you will likely need to keep track of such dates yourself. You could make the seconds a cluster of two integers and test the year part of the date/time for values > 2040 (2039?) and put an appropriate number of seconds into the second integer. However, please check to make sure that Date/Time works properly with the future values.
Lynn