http://rtfm.modx.com/display/revolution20/Reverse+Engineer+xPDO+Classes+from+Existing+Database+Table
// Your package shortname: $package_name = '';
This question has been answered by Bruno17. See the first response.
http://rtfm.modx.com/display/ADDON/MIGXdb.Configuration
Create a new action
System->Actions
right-click 'migx' ->create Action here
controller: index
Create a new menu
System->Actions
right-click 'Components' ->Place Action here
lexicon key: migx
action: migx - index
parameters: &configs=packagemanager||migxconfigs||setup