ctime and ltime in user$ - reset when migrated from 10g to 11g - how to retain original dates?

Greetings,

We are migrating an application database from 10g to 11g.  When accessing the dba_users information, I noticed that the created and locked times where being reset to current date, as if the users were being recreated.

I looked in the user$ table as saw that this was the case for both the users and roles being imported.  We would like to retain this history in the new database, because we have individual useris issued and monitered.  Is there an import method that will preserve this like the passwords?  Can we update the ctime and ltime with a simple script run by SYS?  Or would that impact some system login control process?