Here is an example for this thing; the procedure to make a sequence with an IK part in the middle (frame 11-20) of a 30 frame animation looks like this:

• Start with the first IK frame (11). Dial the PointAts to 1, and by manipulating the IK target (red ring), put the chain into place. Disable the PointAts and fiddle with the FK controls (xyz rotations) until the blocks have the same positions as with PointAt turned on.
• Do the same for the first FK frame after the IK frames (21)
  (- in the remaining frames 1-10 and 21-30 you can do with the FK whatever you want, in the frames 11-20 you can do with the IK whatever you want).
• make sure that in the frames 11-20 the PointAts stay enabled, either by setting keys, or by using a constant in the animation palette.