Samsung Focus Calendar

When placing an appointment on my calendar, I can ask for a reminder between 0 and 60 minutes, 18 hours, 1 day, or 1 week.

Is there a way to make changes to the reminder, i.e., set it to 3 or 4 hours? Sometimes I need to be reminded 4 hours in advance in order to be on time. It appears there is no way to make a change in settings so I fear the times are hard coded.