The bar itself is very simple: a long tube with short tubes welded on the ends configured as 'eyes' on the end of the long tube. Bushings go into these 'eyes'.
The location of the rear roll center is determined by where the rod/bar is vertically located. Generally, just under the axle center line is the norm for the axle end, and horizontally across the chassis from that point for the fixed end. The construction of the fixed pivot, which hangs down from the rear subframe is the most complex bit and is typically a fabricated, tapered box welded to the floor and subframe.
Here is a link to panhard fabrication for Opels. The guy doing the posting, RallyBob (Bob Legere in CT), is pretty darned knowledgeable. You will need to register on this site to view the pix but this is a very good tutorial. BTW the part about crashing if the panhard rod or mounts fails is less applicable with leaf springs as you still have some side axle location. But the car is still going to experience quite a change in handling if it does. I have rallied for a long time with panhard rod equiped cars and never broke one.
Your car's handling will change noticably with this, as the rear roll center will go down a few inches. The car will be quite a bit less tail-happy (less prone to oversteer), and you will need less front roll bar (a smaller diameter front roll bar). At this point, it should be easier to tune F/R balance with spring rates. The hard part of tuning this suspension is the limited selection of T-bars and leafs.
BTW....I just read your avatar and had to laugh!
And, you can look up rear roll center diagrams on the internet to see the difference in a leaf vs panhard rod with a live axle. See if this image works for you:
http://www.chevelles.com/showroom/data/516/medium/ROLL_CENTER2.jpg