oh, and actualy, like i just figured this out by accident 20 seconds ago and i am sooo pleased now, to make an ipo curve for the feilds streignth or any other special setting for that matter, place the mouse over the setting you would like to change and press i.  this will bring up an ipo menu for that specific setting which can not be accessed anywhere else.

 

oh, and right drag to move verticies on the ipo curve.  left click, changes what frame you are editing in