Question: I have to sync iCal on all the computers without having a MobileMe account, I would like it to be "live" because the co-workers have to see the changes right away on their screens, they also need to be able to edit and stay sync on the rest of the LAN.

There isn't a server available - so a server solution such as iCal Server won't work.

Answer: 
One option would be to use [iCal server](http://www.apple.com/server/macosx/features/ical-server.html) which is apart of Mac OS X Server.

Or

Publish iCal calendars with local WebDAV server.
Check out [Zimbra Open Source Edition](http://www.zimbra.com/community/downloads.html). It supports CalDAV for Leopard clients as well as address book Sync. You won't need to setup a dedicated server since it supports Mac OSX as a server platform or you could run it under a Linux virtual machine with VirtualBox/VMWare Fusion/Parallels and make it portable.