The personnel placement company will provide the benefits for the employee, and you just pay hourly rates to the personnel company. The placement agency will handle all of the employees payroll checks, insurance, taxes, social security, etc.
Call temporary placement agencies in your area. Ask for rates and references. When you have a position to be filled, call them, tell them your requirements, and ask to interview five of their temporary workers. You can usually specify if the assignment will be long term or short term.