Create your objects for the registration marks and then apply the
Registration color to their fills/outlines as needed. To apply a registration color, bring up the color dialog and then select "Registration Color" from the color model list box. See the attached image.
The registration color will be printed on all separation plates.
You might also want to check out the CropMarks macro for creating those marks around selected objects automatically:
http://www.oberonplace.com/vba/drawm...cropmarksh.htm