Sorry, this is a work in progress. I was able to create a document via the groovy console as such:
import org.apache.chemistry.opencmis.commons.*
import org.apache.chemistry.opencmis.commons.data.*
import org.apache.chemistry.opencmis.commons.enums.*
import org.apache.chemistry.opencmis.client.api.*
// def cmis = new scripts.CMIS(session)
// println session.repositoryInfo.name
// cmis.printObjectSummary "/"
Map<String, Object> properties = new HashMap<String, Object>();
properties.put(PropertyIds.NAME, "doc123");
properties.put(PropertyIds.OBJECT_TYPE_ID, "D:srv:devServices,P:cm:titled");
properties.put("cm:description", "My document");
properties.put("cm:title", "My title");
Document doc = session.getRootFolder().createDocument(properties, null, null);
Just enter your document type in place of the above bolded text. Next step, WireShark!