A couple of months ago I needed a JCA adapter too. I wasn't able to find any, so I decided to implement it myself. Currenty the adapter is stable and is used in our production systems.
It only supports DIIOP connections and no local connections (so you'll have to use the NCSO.jar provided by Lotus).
I am in the process of putting it all on sourceforge.net but, the sourceforge servers seems to have all kinds of problems.
I am at home right now, but I could probably send you a copy mondaymorning.
Please send me an email at: harm[AT]xbase.nl
Harm de Laat