I do not think that changing the joint parameters or origins of a figure or object mid-stream through an animation would work in a predictable way; those properties are not animate-able. That is, I’m pretty sure that changing an object joint parameters or origin changes the object retroactively back through every previous key frame. Each and every frame would have to be visited and re-adjusted.

Generally, those sorts of parameters are set in an object or figure while developing the figure or prop; before storing the finished object to the library. Making such changes could certainly work at the beginning of a sequence though. You could animate your scene to a certain point and then create a new file from there with the modified joint and or object origin. Set the beginning of the new file as closely as possible to the end of the one before and continue animating from there. The resulting video files could then be edited together using your favorite video editor.

Contributing to your other thread, I think I see now a little more of what you are trying to achieve. While there are limitations to the software, Poser is not arbitrary or capricious. If you are getting wild or unpredictable results, it is probably because you did something wrong, or tried to make the software do something it was not designed to do. I have posted some examples in the other thread, along with some animated pose files, but I see now they are probably not going to help you.

An idea occurred to me though. Seachnasaigh suggested, and I second the idea, of using a control prop. You might try placing a sphere at the contact point between your object and the figure you are animating. Parent your figure to the control prop and use the visibility toggle to hide the prob. Pose the figure to contact the prop featured in your animation and rotate the control prop to rotate your figure. The central origin of your figure will inherit the object’s it is parented to. Again, you will probably have to generate a number of files to pull off the effect. One animation of the figure coming in contract with the prop (cut), another using the rotation-work-around (cut), and the continuing adventure of your animation. Then use an editor to stitch the videos together.

Do not loose patients. There is almost always a work around to any given problem, and there are lots of folks here at Renderosity like seachnasaigh. Folks willing to pitch in and help.