Hibernate version: 3.2.3

How do I specify, in HQL, an update statement that will update a subset,
bound by some number n, of a matching set of records?

In SQL (and Oracle), I could do something like:

update EVENT_TABLE
set STATE = 'new value'
where rowid in
( select rowid from EVENT_TABLE where STATE = 'some value' and rownum <= 5);

This updates the first 5 rows that match the condition STATE = 'some value' even though there are many more records that actually match.

This uses Oracle's constructs of which rownum is used in Hibernate pagination, but not updates as far as I can see.
Can rowid be used by HQL or does it need to actually be mapped
to an unused property in the mapping file?

Is there a better way of doing this?