We figured out one (kind of cheating) way so I'll leave this here in case anyone else has this issue. Fillet all three edges leading up to the corner(s) with a very small radius then set the setback to whatever radius you want the corner to be. Of course, if there is a better way to do this, I'd appreciate it. Thanks.
I don't think that it can be done.
In CATIA V5, you can select a vertex and it will fillet all edged attached to that vertex.
Here in Solidworks, you are limited to selecting edges and surfaces.
Even with the selection filter set to "Filter Vertices" only edges and surfaces can be selected.
The closest thing I could come to was the corner tab under FilletXpert.
Then the corner already has to have a fillet in place and the corner has to have both concave and convex fillets all meeting at the same vertex.