Hi Daryl,
The most current version (1.4) of ns_xml is available at
http://acs-misc.sourceforge.net/nsxml.html
You may need to futz with the Makefile to get it to compile. I set my MODLIBS and CFLAGS as follows:
MODLIBS = $(shell xml2-config --libs)
CFLAGS = $(shell xml2-config --cflags)