You could log into each resource account and share it to the appropriate groups of users (or publicly).
Or, you could run a script similar to the ones at
Zmmailbox - Zimbra :: Wiki if the resource count is too high to do it manually.
Users will have the resources' calendars in their ZWC or, depending on the share level, they can point the browser to http(s)://server.example.com/home/resource@example.com/Calendar.html