If you want to implement your own Inventory Loader to, for example, add Products from something inside your module?
Create a file <customname>.inc.php in the folder modules/Workflow2/extends/inventoryloader/
This file must have the following structure:
[prism field=file language=php]
|LOADERKEY||internal key of your loader to be able to register multiple loader|
|LOADERLABEL||Visible Label of Inventory Loader|
|LOADERCONFIG||Config, visible if Loader of selected|
The CustomClassName could be chosen like you want. It only must equal in class definition and register function in last line.