I have a coil, I didn't get it as emergency contraception but imagine the process is the same.
It felt very uncomfortable having it put in and for about 15 minutes afterwards I felt really crampy and a bit faint. Then I did a poo and felt fine.
Take ibuprofen an hour before the appointment.
Mine was done by my GP, and I think I made the appointment that morning, i.e. didn't have to give them any warning.