Is he not just embedding a VT100 emulator and using NetBeans socket to copy the buffer back and forth? The primary focus of NetBeans integration is to pass basic state forth and not to facilitate a full Vim embed.
To be honest, I don't know. An eclim discussion[1] implies that eclim is using Vim's NetBeans protocol, and the eclim code that I have read is well-organized and the project is mature, so when you said you were having issues with the NetBeans protocol I thought eclim might be a useful reference for you.
