[R-sig-Geo] custom projection (SpatialPolygon)

[Neil Davis]

I have a dataset which uses a custom projection, and I would like to 
import shape files to add maps to the plots.  I was able to import the 
shape file using maptools as both a SpatialLine, and SpatialPolygon, 
however I'm not sure how I can modify the coordinates to my custom map 
projection.  I have converted the standard R maps to my map projection, 
but the spatial objects are a little out of my understanding, as I am 
not sure how to get the coordinate values out of and then back into the 
spatial objects.

Does anyone know how I might be able to modify the coordinates of the 
spatial objects to my projection.

Thanks,

Neil Davis
Research Associate
Institute for the Environment - UNC Chapel Hill