Getting pivot points in mesh has been a bit of problem. If you have ever made doors in Second Life you have probably run into pivot point problems. Creators working with mesh have the same problem.
In 3D modeling programs we can set where we want a pivot point. The problem is that information does not upload into SL. So, there are ways to work around that problem. One of the simplest I’ve seen is here: Mesh pivot point?
Drongle McMahon provides a link in a response post in the thread. it leads to: Change Pivot Point of Mesh which provides more information on moving a pivot point. Drongle made the older post and it is an excellent explanation and ‘how-to’.