Hi @Tumbraegel Thank you for reaching out!
Unfortunately, you cannot install external packages into CodeBook. The environment is fully cloud-managed and supports only set of pre-installed packages provided by LSEG. You can check the list of pre-installed packages by navigating to HELP > CodeBook Libraries&Extensions option.
HELP > CodeBook Libraries&Extensions
The alternative option is to run your notebooks locally where you can install any libraries required for your workflow and still connect to LSEG APIs. You can refer the documentation of the LSEG Data Library for Python for detailed guide, tutorials and examples.
Please continue on this thread if you need help further. Thanks!