If you're lucky enough to be able to use a Debian package,
go to http://www.eecs.harvard.edu/~nr/nbibtex and follow the 
directions for getting nbibtex.

Otherwise, to build NbibTeX requires a C compiler and Lua version 5.0.
Needing Lua means needing the right -I and -l options to your compiler.
Because I live in fear of gnu autoconfig, I have written a ./configure
script by hand.  Maybe it does something useful.

By default, the script installs into /usr/local.

Options to ./configure include
  --debian      configure as for Debian, including installation into /usr
  --compatible  make the 'plainnat' style exactly compatible with BibTeX
