Very conveniently, for the last few months the Sky HD+ box has worked with an external HD connected to the eSATA port on the rear of the unit.
After a software update on the 20th August 2013 the eSATA port is once again inoperative.
August 2013
I spotted this blog over the weekend http://www.aysabtu.dk/blog/.
It explains, in detail, how to connect to a Squeezebox Touch to install a suitable Linux driver to enable a M2Tech hiFace or EDO to work connected to the SBT’s USB socket.