ok, so I contacted them and received this response.
Hi,
Thanks for your enquiry about API access to CoinDesk's Bitcoin Price Index.
As we just launched it, we still need to finalise a few things to ensure the API is stable and performant, as well as provide developer documentation.
We should be able to do this within the next few days, so we will be in touch next week with further information on gaining access.
Please note that this is a free API, and result data will be formatted using JSON.
Kind regards,
Jeremy
Hopefully they will let us know soon.