[R] Adding key to simple plot() function

[Laura Quinn]

I am generating a simple x,y plot to show geographical positions where
point data has been taken. Rather than plot a graph and lay points on top
I've opted to generate the map from the point data, ie plot(-x,-y). This
works fine, though I am wanting to label each point 1:20 and have a key
alongside - is this possible without getting into trellis plots? I have
very limited time available so don't want to embark on trellis functions
which I've never used before..

Also, my x,y  labels currently have a negative sign in front of them which
I'd like to remove, but if I negate the labels they no longer fit on the
graph as my data points are -x and -y...

Any suggestions?

Thanks,
Laura