The addition of module search paths can be achieved for both languages through the corresponding startup script.

For Python modify the mysqlshrc.py file and append the required paths into the sys.path array.

# Import the sys module
import sys

# Append the additional module paths
sys.path.append('~/custom/python')
sys.path.append('~/other/custom/modules')

For JavaScript the same task is achieved by adding code into the mysqlshrc.js file to append the required paths into the predefined shell.js_module_paths array.

// Append the additional module paths
shell.js.module_paths[shell.js.module_paths.length] = '~/custom/js';
shell.js.module_paths[shell.js.module_paths.length] = '~/other/custom/modules';