I've never used them or seen them in use. However, wood bar? I think we will require pix... :-)
Use a cable doubler and inline barrel adjusters to fine tune the pull. http://problemsolversbike.com/products/cable_doubler
Wood handlebars sound like an accident waiting to happen.
I have one bike - a Gazelle with rod-actuated drum brakes-where one lever controls both front and rear brakes. That works OK on a bike with the center of gravity far to the rear. It's set up so that the front brake (which does most of the stopping) acts first, with the rear only taking hold when I pull the lever all the way for s quick stop.
On a road bike, I think you would have to set it up the opposite way to prevent going over the handlebars when you hit the brakes hard. I don't think your braking would be very good at all compared to having independent control.
Or use 2 Paul E-Levers: http://www.paulcomp.com/elever.html
Not cheap, but they do look stylish, unlike that cable doubler.
Well I think wood bars are a bit odd.
What is the stem clamp size?
You can have your wood handle bars turned on a lathe to
accomodate the smaller size of the brake lever clamps.
Some people (especially those who ride fixed gear) don't see the need for a rear brake. The harder you stop, the less effective the rear brake becomes because the rear wheel naturally moves away (up) from the ground while the front wheel pushes (down) into it. There are other factors to consider like where you are positioned.
There are also people who are against anything but a straight line between the brake lever and caliper so as to minimize the possibility of failure. "Suicide brakes" come to mind.
If you want both brakes, I'd say go with what Duppie suggests. My brother has those levers on a really narrow bar and he loves them.
Disclaimer: I am not an expert. These are things I've read but don't know that much about. Check with an expert to be sure.