hello bob,
> The goal is to create a plot of points rather than using openmath per se.
OK, since you are using maxima 5.9.1 --
this web page describes a hackish solution that might be useful:
http://maxima.sf.net/wiki/index.php/Maxima%20helpful%20hints
under the heading "How do I plot a list of points?".
another option is to just print the list of points,
cut-and-paste them into a file, and use an external program to plot them.
version 5.9.2 has a new plot option to plot lists of points.
it will be released shortly.
hope this helps,
robert dodier