You simply cannot, since the storage is attached to the application group and not the application.
That simply mean the following, if you want to do that, then you need to create an application group PER document type.
Or said in another way:
You create a new application group, when you need to:
- store the documents in a separate storage
- have other kind of indexes
- have a different retention period
- have a separation of documents due to business logic (eg: don't mix countries outputs, don't mix different companies output, ...)
And no, again, you simply cannot tell arsload where you want to store your document. This is define with your application group, that means (again), that if you want to store the document somewhere else, then you must change your application group destination with the option -g of arsload. That's your one and only way to do it.