To create a single / mono wiper blade conversion you are basically increasing the throw on the motor arm thus pushing and pulling the middle wiper spindle further so one wiper will wipe the whole windscreen.
Before you start you must have access to a welder or someone who can weld this up for you. Do NOT attempt to bolt or rivet the extended motor arm back together and I also suggest you find/buy a spare motor arm to do this on.
To get to the motor arm remove both wiper arms & blades then the wiper cowling, then the black plastic drain away tray which has panel pop pins through and also sticky insulation underneath it. Once these are all out the way undo the nut on the wiper motor and prize off the motor arm as its on a spline., then remove it from the long linkage that attaches to the spindle by popping the top cup off the ball joint should be free to be removed
It will look like this:
We are going to extend this by 10mm (No more no less) I would suggest a good hacksaw for this job. It is also very important you cut in exactly the same place as in the picture on the upper level of the arm. Once cut find a suitable piece of steel to insert as to extend it.
This then should be welded back together and painted to prevent any corrosion in the future. Once this is done refit to motor in the neutral position not forgetting the spring washer. leaving the drivers side spindle and linkage in place if you wish or you can remove them completely
Now you can either fit the drivers side arm back on to the middle spindle with which ever size blade you find suitable for you.
Or you can get back to the breakers and find a suitable arm off the back of something, I found one from a Ford Mondeo works quite well.
Since ^ that picture was taken I have fitted a different size blade and it now rest inline with the top of the tax disc.
The end result is pretty much the same although the straighter arm the lower down the windscreen the wiper will sit.
http://www.youtube.com/watch?v=eNEtYi1RFWU" onclick="window.open(this.href);return false;&hl=en&fs=1&rel=0&hd=1 
If you want to go that extra mile and have the wiper blade parked up the middle of the screen touring car style then just adjust where the arm sits on the motor accordingly. This will get you an MOT fail though!
