Reading a GOS document in background

I need to be able to find then read a generic object service attachment (wORD document)and pass the binary content to the method document->add_attachment. The key is I need to be able to do it in background. Functions such as DSVAS_DOC_WS_UPLOAD_50 and DSVAS_DOC_UPLOAD_50 work fine but they use front end services. Does anyone have a sample about how to find a generic object attachment then actually read it in background.

Thanks!