Why writing an own class?
Newton comes with a very nice dMatrix class

And I agree with Ventilator that Newton is the better physics engine. At least compared to what is possible in A7. The ODE integration in ODE is insufficient. Fast turning objects can cause colission problems because a higher fps is needed for calculating the physics. A7 does not allow to e.g. double the physics engine framerate. It's always tied to the engine fps (unless I missed something).
I know that ODE can do more than what is possible with the current A7 integration, but that doesn't help as long as the internal interface stays the same in A7.

For my test project I saw no way to do this properly with the integrated ODE. With Newton it works a lot better (but still needs tweaking).
And thanks to Ventilator and VeT there is a really easy to use wrapper available.