The ginger is very easy to do. Get about 2 ounces fresh root ginger and grate it using the fine grater. It should be quite juicy if it is fresh and then press the grating lightly in a garlic press to extract the juice. I am sure that you can also use about 1 to 2 teaspoons of ginger extract.
The dandelion is a little more complicated I use fresh root which I chop roughly, add it to the lemon/grapefruit juice and liquidize it. Then pour the juice and dandelion through a sieve pressing it slightly to make sure the maximum amount of sap is extracted. It should turn the juice slightly creamy. Alternatives are to add between 1 and 2 teaspoons of dandelion tincture or 1 to 2 teaspoons of ground dry dandelion root. The dry dandelion root can be herbal or from a dandelion tea bag.