Visio Guy recently posted an excellent article regarding finding the length of a connector, Simple Cabling Shape with Length Reporting
http://visguy.com/vgforum/index.php?topic=7258.msg30514;topicseen#msg30514 However, it uses features not available to we users of V2007 and older. Well, we may be aging dinosaurs, but, we're not extinct...yet.
So, I did a scaled down version of Visio Guys' post. There are two shapes on the stencil, one for a normal 1D line and the other for a connector shapes. These are unique only in that there is a formula in the Event double click cell calling the macro. There are two macros in this document. One , as mentioned, is called directly from the shapesheet of the aforementioned shapes. The second is a macro that is associated with the document. It may be run as any ordinary macro, just be sure to select a shape first.
The "embedded" shape could double as a dimension line...Just stretch it between two points and double click. But, it's not as fancy looking, nor does it have all of dimension shape features. Just saying.

Enjoy!
wapperdude