Nope, you can't enter a pair of co-ordinates, but you can select a destination on the map using the crosshairs. No lat/log display with the map though.

You could narrow things down somewhat by creating a grid of lat/log co-ordinates for the general area of interest and adding these to the map as custom POI. The degree of accuracy will be determined by how fine your grid is. Not an ideal solution, but possibly a workaround...