The Sky+ HD box isn't a Pace, it's manufactured by Thomson, so it's best to use their codes from the Harmony library. It's listed as Thomson PVR, model DSI-8215.
That should work perfectly (does for me). The only thing I'd suggest is adjusting the delays in the 'Device Options' menu, put the power on delay at 1500ms and the others to 0ms, then the Harmony will behave just like the supplied remote.