How can I use KanBo to manage the approvals of documents?

Could you advise if organizations use the KanBo tool to manage the approvals of documents, and if there is a way documents which are stored in the document library can be set to read only once documents have been approved? Is there a way to automatically assign specific reviewers/approvers to a card?

For example, you create lists: Documents to review, Doing, Approved and Declined. When you add multiple attachments to card and it go to Approved list all attachments (stored in SharePoint library) will be set to read only.