Xcode was the official development IDE for WebObjects 5.3 and below.  Since WebObjects 5.4, WOLips is the "official" toolset.  You can use Xcode 3 on Leopard to compile WO projects, but that's about it.

Finding deprecated API in Xcode

When you compile and Xcode tells you to use the -deprecation flag to see details:

• Select Project/Set Active Target/Application Server
• Then select Project/Edit Active Target "Application Server"
• On the left hand side of the Target information window you'll see Java compiler settings under the "Settings/Simple View". Select it.
• Under Java Compiler Settings you'll see a check box for "Show usage of deprecated API". Checking this box will give you details in the build panel of what API has been deprecated in your code.