Reports are that Film 4 HD is testing on the following frequency:

12324 V 29500 3/4 DVB-S2 QPSK.

The channel is "tagged" as 3844.

And is encrypted, as it is expected to be available with a Sky HD subscription, similar to E4HD and More 4 HD.

Film 4 HD is expected join the Sky platform in September 2013

However, you cannot manually add this channel to a Sky HD digibox due to the symbol rate of 29500 not available to manually select.