Jitter keyframe timing?

Thanks, but that's not what I am after.

I'm asking if there's a non-destructive method of adjusting the timing of keys.  The whole point is to keep the keyframes aligned on the timeline, so that editing is easier (as opposed to them being randomly scattered).  That plugin simply moves the keys on the timeline, which is exactly what I'm trying to avoid.  I was hoping there might be a way to internally shift the timing of keys (a sort of ease in/out attribute of each key, but one that actually shifts it, in reality, in time) without actualy causing the displayed keys to be shifted, so that a clean grouping of keys for each 'pose' is maintained.

I'm also not after one that just does it randomly or globally.  I want to do specific staggering (early/late) of certain keys from the 'main group' (keys that are initially in the same time), as in un-syncing the wrist and forearm from the movement of the upper arm... and that would be done manually, and specifically (as far as amounts, and whether it's before or after the main keys).  I still want to manually shift/animate, in order to do things properly (not random).   I'm just looking to see if there's a means to do that, but without breaking the visual lining up of keys on the timeline.