I'm not too familiar with it, but isn't Eclipse an IDE for interactively developing and debugging applications, rather than an automated tool that would be used within a build process? I believe that Eclipse developers typically use automated tools such as Ant for actually building projects developed in Eclipse (VBP does include an Ant action).
That said, if Eclipse supports a command-line interface, you could call it from a Run Program action.
http://www.visualbuild.com/Manual/runprogramaction.htm
If it supports a COM automation interface, you could call it from a Run Script action.
http://www.visualbuild.com/Manual/runscript.htm
In either case, you could also wrap it in a custom user action.
http://www.visualbuild.com/Manual/userdefaction.htm