Drawing a circle

[Chip Taylor]

I am running MapServer as a CGI under IIS 6. We do not use PHP and would
prefer not to have to install it.  I would like to draw a circle on the
resulting map providing not a size as you would for a symbol, but have the
map extents [mapext] determine where the circle is drawn.  The circle would
be sized so that the outer border of the circle touches the top center and
bottom center of the map.  I know that I can do it client side will some
complex calculations or do it with GDI server side but neither of those are
really what I am looking for.  Can anyone tell me if what I am asking is
possible with just MapServer CGI and a Map File?

If not, are there any "helper" packages such as Chameleon that would make
this easy to implement?

Thank you in advance.
Chip Taylor