I'd say make hibernate work in OSGi container isn't an easy task.
Split-package issue everywhere is one reason, but still have other reasons like classloader issue.
You have to repackage hibernate lib yourself or use some 3rd party lib which repackage hibernate lib.
FUSE ESB 4.x has a jpa-osgi example shipped with kit, you may need take a look, it use hibernate libs packaged by springsource.
We've also built higher version of hibernate lib to make it works in OSGi container, but it's not free, if you have fuse subscription you can use that channel to contact.
Btw, if you can change the JPA implementation then you can try with openjpa, it works better in OSGi container.
You may also want to look at FAB that makes deployment applications to the OSGi container much much easier
I posted a blog with some links for material with video introductions, further documentations, and examples
Deploying and using Hibernate should then become much easier. The other day a person leverage this to get his Hibernate working.