How do I apply a bevel effect without the black edges?

[Neyjour]

Is it possible to apply a bevel effect without a black edge?

My maps all have a black border that's fairly thick. When I apply a bevel effect (to give the terrain edge a bit of height) the black parts of the beveling make the black border become even thicker (right arrow), which I don't like. What I want is to have the lighter/bright bevel effect (left arrow) around the entire terrain border, but Paint Shop Pro (the program I use) doesn't seem to have the ability to do that.

Is it at all possible in another (free) program? I do have the GIMP, but don't have much experience with it. I only use it periodically for cropping...


EDIT: I figured out a way to do this, but it's extremely time-consuming and tedious, so if anyone knows of a better way to achieve it, I'd still like to know please!

What I'm doing is:
1) Open the base terrain (without my black border) and duplicate the layer.
2) Apply the bevel to the duplicate.
3) With the Freehand selection tool, select a portion of the edge that's bright.
4) Invert the selection and delete.
5) Duplicate the original base terrain again and move it to the top layer.
6) Change the angle of light slightly until a portion of the edge (right next to the one I previously did) is bright.

Then repeat steps 2 > 6 over and over and over and over and over and over and over and over and over and over and over and over and over...

There has GOT to be a better way.