I would suggest you look online and see if there is a Ford Mondeo forum. We found from the Fiat forum that our car would run on 50/50 veg oil/diesel without any hassle. You need to replace the fuel filter more often (annually) as it will block up more rapidly as the oil is thicker and pulls more of the rubbish out of your fuel tank if you let it run low. Another hint is keep your nose working when around other Mondeo diesel's - if you smell a chip shop, ask the driver what modifications they have made
As to putting the oil in, simple, get a funnel and pour it in. However, veg oil is now 95p a litre so not a lot cheaper than diesel. The main satisfaction is knowing that the government isn't pinching all your money in tax.