We are not using the Kentico Libraries to upload documents to sharepoint, but we use Microsoft.SharePoint.Client. Here is an exaqmple how to upload an document with the MS Sharepoint API : http://stackoverflow.com/questions/9847935/upload-a-document-to-a-sharepoint-list-from-client-side-object-model.
Is this the right directions or do you want achieve something else?
It is really nice to combine Sharepoint with Kentico, in this way you can use the cloud as storage for you're documents and edited them where you want with MS Office online.
If you have questions or problems let me known and maybe I can help you.
If this answer helped you, please vote for my answer :-)