By turning on biped trajectories, selecting the center-of-mass track, and turning on Sub-Object: Trajectories, you can select a key on the trajectory. Then either use Bend Horizontal in the Keyframing Tools rollout to bend the trajectory about the selected key, or simply move the key. You can move center of mass trajectory keys either horizontally or vertically. This allows you to view the entire trajectory of the center of mass and bend or edit the trajectory.
Tip: You can select the center of mass's horizontal or vertical tracks by clicking the appropriate button in the Track Selection rollout.
Warning: Do not use 3ds Max trajectories (Motion panel > Trajectories text button) to edit biped trajectories.
To bend a biped trajectory:
On the Biped rollout of the Motion panel, expand the horizontal bar (click the plus sign at the left) to display the Modes and Display groups.
In the Display group, turn on Trajectories.
The trajectory is displayed in the viewport for whatever biped part is selected.
Warning: Don't click the Trajectories button next to Parameters. That is for other scene objects, not bipeds.
At the top of the panel, below Selection Level, turn on Sub-Object, and choose Trajectories on the drop-down list if it isn't already displayed.
In a viewport, select as many keys as you want on the trajectory.
If you want to bend the trajectory open the Keyframing Tools rollout and locate the Bend Horizontal spinner. Then adjust the Bend Horizontal values as desired.