Use dtcm_insert from the command line to insert appointments on your calendar. For example:
system% dtcm_insert -d 11/1/1994 -s 11:30am -e 12:30pm -w workout
Appointments for Tuesday November 1, 1994:
1) 10:00am-11:00am one-on-one
2) 11:30am-12:30pm workout
3) 12:30pm-1:00pm eat lunch
Calendar automatically prints the appointments scheduled so you can see that the new appointment was inserted.