We are indeed planning to add special patterns to support the BPT projects sizing. What we have planned and are now evaluating is the addition of two patterns one for processes and another one for process activities. We need to fine tune it with the information and experience we gained with our beta program'. At this stage we do not have the date when it will be made available.
In the meantime you can still size BPT projects like a standard project and using the days of service pattern to account for the need effort to design and build the process.
Your comments on our approach are more than welcome.
Thanks for your email!