Hi,
Since you've opened a thread couple of months ago, I am not sure whether or not you are still looking for an answer. However, I would still assume that you have not received any answer on your query and I will try to help you.
Before I could answer your query, I would like to know where are you trying to import these certificates to. Do you have a SEMS (previously known as PGP Universal Server) ? Can you please elaborate on what you are trying to achieve?
Best Regards,
bipshr