1. Select an object.
2. Click Animate in the main tool palette.
3. Click Scale Keys in the lower tool palette.
4. Enter a scale factor value and a frame range. To alter all objects in a scene, enable the All objects option. Click OK to accept or click Cancel to abort.
5. All keyframes for the current object, or all objects, between the inpoint and the outpoint will be scaled by the value defined.

Frame range - Defines a range of frames which this function will effect.
Centered on - Defines a reference frame for scaling.
Scale - Defines a scaling factor which the keyframes' position in time will be scaled by. (i.e. a value of 0.5 = 50%)
Ripple All frames after the last frame scaled will be offset such that they remain sequenced with this last frame.
All objects - When enabled, forces the function to effect all objects in a scene.