Take a look at this tutorial, it describes how to do this with one field, for a number of fields, you need to modify the code a bit:
http://acrobatusers.com/tutorials/change_another_field
Give it a try, if you cannot get it to work, please just come back and provide more information about what you tried and what the outcome was, and we will help you to get a working solution.
Karl Heinz Kremer
PDF Acrobatics Without a Net
PDF Software Development, Training and More...
http://www.khkonsulting.com