http://www.hometalk.com/search?filter=squeaky+floors&search=&zipcode= Some answers on this link to other members who have asked the same question. Maybe some of these fixes will help. Good Luck!
Creaking wood is caused by the wood members rubbing together. Steps on the other hand creak because the construction methods have begun to fail causing the wedges used to come loose and allow the step to move up and down.
The simple fix for floors is talc powder. Or corn starch. put some on the floor and work it into the gaps between the floor boards. This will act like a lubricant making them a bit more quite.
The steps on the other hand a bit harder to fix. Either you need to access from behind the steps, by removal of the ceiling under them, then using a hammer hit the wedges and make them tight once again. Once you have done that a pin nail gun or hot glue gun will make them quite.
If you do not want to open up under the stairs, the trim moldings that are just under the front of each step can be removed, glued and then nailed back into place. This will prevent the front half of the step from moving up and down. There is really nothing you can do to stop the movement near the rear of the step without removal of the step backing. But it should help a bit.