Oracle sequences for PK generation

Hi,

I am to create a (small) WO app that sits on top of an existing Oracle  
DB. One requirement I cannot change is that each table has an  
associated sequence for the primary key. So I cannot use EOF's  
automatic PK generation but I have to get the next value from the  
corresponding sequence. What options do I have? What have others done  
in such a situation, what are your experiences? How do you access the  
sequence? Model it as kind of an entity? Use raw SQL? Use the adaptor  
delegate to provide the PK? Simply trat te PK attribute like a  
"normal" attribute and assign a value to it?

Thanks for any help
---markus---