I'm guessing you want to alter the [Date] field to do this. You might try this on ONE sample file to prove that it works. Date calculations turn out to be sort of strange, but they make sense. Here's the definition of an expression column that I just used as a test:
FormatDate(Math(convertdate([Date]) + 3 + ((20 * 3600 + 5 * 60 + 12)/86400) ), MM//dd//yyyy HH:mm:ss)
Make an expression column with that definition and you can play around with it. The middle part, with the Math() function is calculating a new date based on the value of the [Date] field. I'm adding 3 days, 20 hours, 5 minutes, and 12 seconds. The FormatDate function is being used so we can see the output in a human readable format. I *think* that for just doing an alteration of a Date type field, you just do the Math() on it and then stuff that back into the correct field. Something like:
=Math(convertdate([Date]) + 3 + ((20 * 3600 + 5 * 60 + 12)/86400) )
I just tested that and it works on a Music file. I don't have image support (MC20 for Mac), so I can't test that, but it should be very similar.
Good luck to you.
Brian.