Down load & save comet data from
http://www.cfa.harvard.edu/iau/Ephem.../Soft01Cmt.txt.
Open Starcalc
select services
select asteroids & comets
click on the comets radio button.
click on import data
browse to downloaded & saved file.
Click on yes to remove previous comet data
Select required comets to display.
exit asteroids & comets