I've done some searching and read the mapping DTD but haven't found a way to generate a property value from a sequence without making it the ID for the class.

<class name="MyClass" table="MyTable">
<id name="oid" type="long" unsaved-value="null">
<column name="oid" sql-type="number(38)" not-null="true"/>
<generator class="native">
<param name="sequence">oidseq</param>
</generator>
</id>
<property name="anotherId"/>
</class>

MyClass has a property called 'oid' as its primary key and the sequence generation works fine. How do I tell Hibernate to generate the value for anotherId (a non primary key property) from a database sequence?

Not possible.