I could be wrong, but it doesn't look like Class::DBI::Oracle does anything special to make sequencing work unless you call set_up_table. Not sure about possible issues with your old version. Check the changelog and try asking on the Class::DBI mailing list.
Comment on Re: Re: Re: Re: Class::DBI::Oracle and views
Good lord, do I feel stupid -- after hours of poking, and even testing on a system that has a more recent Class::DBI -- I discovered that the problem was a typo in my package declaration.
*sigh*
Thanks for all your help, though. I do appreciate it.