1) Share the folder/mailbox and have the users make a permanent connection
to it.
See http://www.howto-outlook.com/howto/permissions.htm
2) Have them enable the Outlook Address Book option on the contacts folder.
See http://www.howto-outlook.com/faq/contactsinaddressbook.htm

Signature
Robert Sparnaaij [MVP-Outlook]
Coauthor, Configuring Microsoft Outlook 2003
http://www.howto-outlook.com/
Outlook FAQ, HowTo, Downloads, Add-Ins and more
http://www.msoutlook.info/
Real World Questions, Real World Answers
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> A small group of our users user a third party application that
> incorporates a plug in for Outlook. It works fine, except that it
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>
> QH