Problems using 'set key on outside box'

Hi,

I've got some problems putting my key box outside the plotting area by using 'set key on outside box'.
a) The box of the plotting area and the box of the key overlap - not in the gnuplot window, but when I use 'set terminal pslatex' to include the plot in my diploma thesis. I'd like to have some margin between it. Is there a possibility to add it? Or do I have to use 'set key at ...' ? Or manual editing of the resulting .tex file?
b) When the key moves from inside to outside of the plotting area, the width of the latter one shrinks (I don't now how to put it. When the key is inside, the plotting area has e.g. 400_px x xyz_px. When the key moves to the outside of the plotting area, the plotting area and the key together have a width of 400_px, maybe 300 for the plotting area and 100 for the key. I still would like to have 400 for the plotting area *and* 100 for the key). Maybe this can be done by adding 'set size 1.2,1'?

Thanks,
Reinhard