NLI-tcl implements the most useful (imho) subset of the NLI API, and is entirely based on T Poindexter's sybtcl. It seems to work. I used it to implement a "swanServer" daemon which would accept English language questions from a client program, process using NLI, and return answers to the client.
One reason why I went to the trouble to make the extension was in the hope of integrating NLI with the Xess spreadsheet, for which I also have a Tcl extension. NLI has a nice GUI with lots of cool features including a good report writer and some graphics -- but they print their graphics using xpr (ugh), not PostScript. So the graphics look fairly dismal on paper. I was hoping, and still hope, to get the time to integrate NLI into Xess, which has really superior PS graphics capability.
NLI-tcl is not yet ready for posting, but if you write to me personally I'd be happy to give it to you for a beta test. It seems to work, but I haven't been able to bang on it enough to really know.