how to use custom Python distribution properly

[schussda]

I read
https://hatch.pypa.io/latest/how-to/python/custom/
https://hatch.pypa.io/latest/tutorials/python/manage/

but its not quite clear for me how to use this i tried this in hatch.toml:

[envs.default.env-vars]
HATCH_PYTHON_CUSTOM_SOURCE_PYIR3_12 = "https://github.com/indygreg/python-build-standalone/releases/download/20241206/cpython-3.12.8+20241206-x86_64-pc-windows-msvc-pgo-full.tar.zst"
HATCH_PYTHON_CUSTOM_PATH_PYIR3_12 = "cpython-3.12.8+20241206-i686-pc-windows-msvc-pgo-full.tar/python/install/python.exe"
HATCH_PYTHON_CUSTOM_VERSION_PYIR3_12 = "3.12.8"

Afterwards i was expecting to be able to install it via
hatch python install pyir3.12
but its not available