Letting 3 users update Palm schedule?

At my office a user has a Palm handheld that he uses for his calendar and contacts. There are 2 other users that need to update and add meetings but they are on different computers. Is there a program or a way of sharing this information so they allcan edit the information and then it be updated when the palm is synched? I need for them to be able to do it at their own desks and for it to be as simple as possible because it will be done many times a day. Thank you,
George