There are set of fake tattooing pens you can buy in art shops, which allow you to just draw straight onto the skin.
However, if you've got a very willing cast, a good budget and you talk to the right people in the tattoo buiness, it is possible to get a proper tattoo that only has a life of about three to four months.
The work would need to be done at least two weeks before production to allow it to heal properly.
The needle only goes into the top layer of skin and therefore doesn't become permanent. They cost the same as a regular tattoos and it's a case of finding a tattooist who specialises in this work.
The easiest way, however ,is to use temporary tattoos, as said earlier. If you do, remember to get multiple (lots) copies of the same piece of flash (tattoo design), they really do come apart very quickly under film conditions.