Actually it is relatively simple. Lots of patience and some basic skills and it can be done.
It is basically a copy/paste work with saving every finished frame. Since there will be 16 poses (used by the CIV animations) for 4 angles, for three actions it is precisely 132 images (one action consists of doing nothing, but standing still).
P&M files use smaller number of frames (12) and some of those are repreated which made it so efficient and easy to implement numerous new animations e.g. cavalry needed just 16-20 images per each working animation.
The difference is considerable as you can see, but should be worth the effort, at least in some cases such as these Landsknechts or new artillery animations.