I'm developing a software which is based on OpenEMPI.
This is a Spring+Hibernate application (with an EJB3 interface and Struts + Ext GWT/GXT GUI).
The Hibernate entity configuration is mainly done through source code annotations. We have also an hibernate.cfg.xml and a persitence.xml.

The number of fields, the name of fields and the type of fields of my Person entity (it's the entity which has a central role) are only be able to be determined when I actually import a set of data.
Discussing of fixing my data schema or using NoSQL or other techniques can be a different forum. Now I want to concentrate to a specific pattern, what I want to apply:
Custom Fields Pattern
With this I can persist a collection of properties stored in a HashMap.

My problems:
1. The EntityManager is abtracted away from me, I cannot see such a class, so I don't know where/how to apply CustomizableEntityManager.
2. I don't know what to do with HibernateUtils class, where to put it.
3. OpenEMPI uses Annotation style Hibernate configuration. We have a hibernate.cfg.xml, that's a place where the dynamic-component XML configuration can fit in. But I don't know if a hybrid annotation+XML type Hibernate configuration would work.
4. There are also a MappingManager and the XMLUtils classes.

Of course my main problem is that I don't have deep enough knowledge of Hibernate and Spring to solve this issue on my own.
Any help is appreciated.
Thank you in advance.