dimensioning in Blender

I need to print my mechanics drawings.
And I need to draw the dimensions of some edges, rays, angles.
If you know about mechanical drawing you know what I mean.
Tell me how to do it or give me link tutorial with blender 2.5 beta.
thanks

As you see i go on pretendiong to do with Blender anything i did with Autocad and Rhino

This script used in this tutorial may work.