I read the thread and it's still fuzzy to me. When you say 'built in' do you mean I do not need to download/install Mac OSX Server on my just-updated OSX 10.4.11 Mac first?
Second, what do I open to do the activation? I read an Apple doc that said to open "Server Admin" --- where is that? Here's what it says:
For 10.3 or later
1. Open Server Admin.
2. Select the Web service from the desired server in the Computers & Services list.
3. Click on Settings.
4. Click Modules.
5. Enable or disable the php4_module as desired.
6. Save the changes.
7. Restart the Web Service.
Apple also refers to and Mac OSX Server web site, but provides no link.