unless you have intellisync, you can't sync - you can make the items
available as an ics file for users to download, either individually (best if
you have a lot of people with older versions) or as a multievent ical. Do
you want to upload the icals or have them created on the fly as someone
wants to download the event?

If on the fly, your best bet for help is from people who use the same web
development language your site uses - i.e., if the site runs on iis and uses
asp.net, look around asp.net sites. if it uses php, check php help sites.
You