Hey Aaron, i am working with this now too and i noticed that ifi don't set the TimeSlotInterval at all itseems to default to the number of lines it can display in the given area. So i have a 12 hour span here, if i adjust that to 6 hours i can see the fifteen minute marks. At that point if i set TimeSlotInterval to ThirtyMinutes the 15 minute lines are gone. So it seems like you can only adjust up to what can be displayed based on the available space.

DateTime time = _dayView.FirstVisibleTimeSlot.StartTime;
TimeSpan ts = new TimeSpan(time.Hour, time.Minute, time.Second);
us.StartDate = us.CalendarInfo.ActiveDay.Date;
us.StartTime = ts;
us.EndDate = us.CalendarInfo.ActiveDay.Date.AddHours(23);
us.EndTime = ts.Add(new TimeSpan(12, 0, 0));               
us.PrintRange = SchedulePrintRange.SpecifiedDateRange;
us.PrintStyle = SchedulePrintStyle.Daily;
us.IncludeCalendarInfoNotesArea = true;
us.TemplateDayView = new UltraDayView();
us.TemplateDayView.TimeSlotInterval = TimeSlotInterval.ThirtyMinutes;
//us.PrinterSettings.DefaultPageSettings.Landscape = false; //Does nothing on printing
//us is the UltraSchedulePrintDocument

I hope this helps,

John