Using WOBuilder with WOLips - the general consensus is: Don't.
WOBuilder was deprecated with the release of WebObjects 5.3 and eliminated alltogether with the release of Leopard and WebObjects 5.4. In that same time the Component Editor in WOLips has taken massive strides in functionality and ease of use. Many (though not all) users feel that they are as productive with the Component Editor as they were with WOBuilder.
For legacy users, the original article is presented below:
Unfortunately WOBuilder requires a special interaction with Xcode to be able to function properly that the WOLips team is currently unable to reverse engineer. This means that to use WOBuilder, you must have Xcode running in the background. WOLips will attempt to help out by keeping your .xcodeproj files updated as you work on your project, but you must leave Xcode open to actually run WOBuilder properly. If you are not using Xcode 2.1+, then you need to turn on .xcode writing instead of .xcodeproj writing (see the Window=>Preferences...=>WOLips=>Build preference panel).