How to retrieve accumulated transformation matrix from bone deformation

Hi,
I’m playing around with implementing implicit skinning from http://rodolphe-vaillant.fr/permalinks/implicit_skinning_project.php - so far I have managed to gather anything from the mesh I need and added a UI checkbox conditionally enabling the feature, but I struggle to retrieve the accumulated transformation matrix for a vertex. To be more precise, I need the local transformations done within armature.c/armature_vert_task. There are several places where matrices are manipulated and used, but I can’t get my head around how they all play together. Does someone have a hint (or even better, a solution) for me?

Thanks in advance.