It's not a graphical tool - it's an add-on that was available back in the days of VFP 5.0 that allowed you to use Visual Modeler as a modeling tool for VFP. I found the link to it http://msdn.microsoft.com/vfoxpro/downloads.asp but unfortunately the download is no longer available.

This tool also used to work well enough with Rational Rose where you can do the forward and reverse engineering - it had some bugs but it was better than nothing.

Again, it's not a graphical tool that works on it's own - it's an add-on that is no longer available... You'll have to contact Markus Egger to get it if he's willing to give it to you.