[R] Non-standard axis plotting

[Laura Quinn]

I am trying to plot positions on a grid where the x and y axis equate to
longitudinal and latitudinal co-prdinates respectively. As these
co-ordinates are southings and westings, i need the origin of my graph to
contain the two highest values of each co0ordinate, with the values
decreasing in both respects along both axes - I cannot seem to find any
function within r to allow me to do this.

Also, how can i avoid r automatically rescaling my data - my data points
are not evenly clustered and I want the scalings on the x and y axes to be
the same, so that they represent a true picture of the spatial scattering.
R rescales the data to fit the best "square" in each case -
misrepresenting the scaling of my data. I have looked at all the options
within par() and axis() and nothing here appears appropriate.

Thanks in advance..
Laura