How do I to create ICS files on Public folder?

Our company needs to enable our external user to access our company’s calendar. This we intend to do by creation of an Internet Calendaring and scheduling (ICS) on our company’s public folder. Majority of these outside users shall be accessing the schedule using Outlook, iPad or iPhone. For our employees, they access the schedule by the public folder which is available on the company’s Exchange Server.
It is possible to create the ICS files through outlook. However, I find it necessary to combine that with the ability to manage and Update the so created ICS files from the Exchange server instead of doing this on the PC. Since I have a Webdav server account that hosts the ICS files does anyone have an idea how I can set up to create the ICS files on the public folder so as to create the ICS files for the external users to make them access our calendars? Do we have other applications that can be used for this?
