Blender is bundled with a version of BAM. To update this version, first build a new wheel <http:https://pythonwheels.com/>_ file in BAM itself:

python3 setup.py bdist_wheel

Then copy this wheel to Blender:

cp dist/blender_bam-xxx.whl /path/to/blender/release/scripts/addons/io_blend_utils/

Remove old wheels that are still in /path/to/blender/release/scripts/addons/io_blend_utils/ before committing.

This is the way that Blender runs bam-pack:

PYTHONPATH=./path/to/blender_bam-xxx.whl python3 -m bam.pack