I was playing around and got the upgrade to mostly work. The changes in the core functions were pretty easy to spot. Also, the script path to index.php?option=com_roundcube wasn't that hard to find either.
However, when dealing with access the database things are a bit different. I left the functions from joomla-roundcube 0.1 and they still work.
I've had enough fun for now. I really like having this integrated with my joomla so I can use the admin backend. However, I think the new features in 0.1.1 are really worth having.
So, for now I think I will keep a nice standalone roundcube 0.1.1 going and leave the Joomla version at 0.1 until someone a bit more skilled can finish an upgrade.
I'll try to attach my hacks for anyone who's interested. Please let me know if anyone make some progress on this.
Peace,
Joomla_Roundcube_011.zip