The supported properties can be found in the wildfly-nosql GitHub project.
When I first read the Hibernate documentation, I thought that all properties should be entered under <properties name="default"> ... </properties> like in the persistence.xml, but this is not the case.
An example client can be found in the README: https://github.com/wildfly/wildfly-nosql/blob/master/doc/README.adoc#connecting-to-mongodb-from-wildfly
All supported properties are listed in this schema: https://github.com/wildfly/wildfly-nosql/blob/master/mongodb/subsystem/src/main/resources/schema/wildfly-mongodb_1_0.xsd
With the help of this scheme I tried to connect an external MongoDB cluster, including a user profile, and it worked without problems.