Overriding animation for a custom "JointLookAt" PlayableBehaviour

Hello dear aficionados

I'm exploring options to customize a Timeline PlayableBehaviour to override a running animation for a "LookAt" Timeline event. The wish is along these lines; to have a track for a character with running animation, where at a given time and duration we wish to ease in an override of the animation grip on a joint, such as a neck joint to look towards a specifiable direction. This could take place as 3 different Timeline clips - ease in, maintain, and ease out. Or with a single clip and editable curve of weight influence. I've already managed these things, except that the animator does its thing and overrides any changes done to a Transform/Joint. When doing these things outside the Timeline editor, overriding an animation could be done in LateUpdate, but seemingly I can't find any similar processes to imbed my changes to when approaching it as a PlayableBehaviour or PlayableAsset. I hope there are some solutions outside of coding some framework to supply LateUpdate events to a timeline, as that will come with a heap of issues.

If my explanation is inadequate, let me know and I'll try to visualize the goal and issue.

Any clues or info about how to move forward with this issue would be appreciated.
Kindly
Daniel