That is not an easy one as the Tax people are clamping done on this. You will have to prove that your "staff" are self employed and they would have to fill in forms etc. Its not easy as they will come knocking on your door if they don't pay and being custom's as well now they do have a lot of powers!!
The best thing is to look at the tax office web site, look up self employed and make sure you can fullfill the requirements.