I had a useful meeting with Richard Jones of Cottage Labs, in which Richard was able to give some much needed insight into the SWORD protocol. With that insight and my experience of Mahara, we were able to make a start on drawing up detailed specifications for the Portfolio Commons project.
Now that I have a more complete idea of the transactions required to make a deposit from Mahara to a repository using SWORD, I can make a start on building the required interface elements in Mahara.
Richard also showed me the Simple Sword Server, which will serve as a useful substitute for a live repository while I do some basic testing.