I want to give credit to the follow person and website for a solution that works, but requires a lot of effort. Scott Lowe has a blog entry that gives a process that is useful in making the conversion to OmniGraffle stencils.
http://blog.scottlowe.org/2007/01/18...ng-on-the-mac/
Here’s the process I’m using:
1. Place a single item from a Visio stencil onto a blank Visio diagram and save that diagram as a PNG image. (Override the default screen resolution to custom resolution of say 400dpi.)
2. Move the PNG image to my Mac and copy the contents of the PNG to the clipboard. OR drag the PNG directly onto an open OGP document.
3. Paste the image into a stencil in OGP. Tweak the size, connection points, etc., until satisfied. Move into a OGP stencil file and save occasionally.
4. Repeat as needed.