For our intranet, we simply designated another computer as our intranet server, and kept it behind the firewall. Our main webserver (for external use) is outside the firewall, and our intranet server - being inside the firewall - can be accessed by anyone within the company. Once you leave the company, the firewall keeps your intranet secure.

You just install ActivePerl or whatever you're using the same way as you would for a normal webserver - the firewall keeps the intranet from being accessed by anyone outside the company. That's presuming you don't want your intranet to be accessed by employees at home - if you /do/ want your intranet access at home - while keeping it away from J. Random User, then you'd need to set up a VPN or something, which is /way/ beyond my scope of explanation :)

"I don't want the world; I just want your half"