I think the annotation you are looking for is:
public class CompanyName implements Serializable {
//...
@JoinColumn(name = "COMPANY_ID", referencedColumnName = "COMPANY_ID", insertable = false, updatable = false)
private Company company;
And you should be able to use similar mappings in a hbm.xml as shown here (in 23.4.2):
http://docs.jboss.org/hibernate/core/3.3/reference/en/html/example-mappings.html