There are a few UK based forums where people have done a lot of research into biodiesel and vegtable oil. I used to have an old diesel 106 that I was going to convert to run on standard vegtable oil but the engine blew before I got to do it.
From what I remember, the main concern is the diesel pump. In the UK there is a mix of Lucas and Bosch injector pumps fitted, sometimes even mixed on otherwise identical models (The puegoet 106 uses both depending on the supply available to the factory when the car was made). The Bosch pump is fine on biodiesel or even straight vegetable oil (svo), but the Lucas pump suffers terminal failure after only a few minutes of biodiesel. The Uk forums can help you identify what type you have fitted. You have to be careful about the fuel seals and lines too, but thats much easier to check if they are biodiesel compliant.
I've heard a lot of the things that Ford said in their reply, but most of them are easy to get around. I believe the paint stripping is due to the chemicals used in the transformation from waste vegetable oil to biodiesel. The viscosity of biodiesel can be a problem, but I was going to get around this by installing a twin tank system similar to that used by lpg systems. You start the car on mineral diesel, and have a second tank containing ordinary vegetable oil. You need to install a heater in the vegetable oil tank to make it flow nicely, and once its up to temperature switch over to the oil. Before you stop the engine you switch back to mineral diesel for a few minutes to clear the fuel lines of oil so they don't clog up when it gets cold.
Have a look at:
http://www.vegetableoildiesel.co.uk/forum/index.php