Hardware Skinning

Dear all -

Does anyone know if/how it would be possible to use

 mat4 matrix = p3d_TransformTable[transform_index.x] * transform_weight.x
              + p3d_TransformTable[transform_index.y] * transform_weight.y
              + p3d_TransformTable[transform_index.z] * transform_weight.z
              + p3d_TransformTable[transform_index.w] * transform_weight.w;

in conjunction with the hardware instancing index (gl_InstanceID)?

I would like to use HW skinning not only for one instance but several ones based upon HW instancing?

Thanks !