I doubt any non sky product would be able to change the channel of the sky box.
My JVC comes with a so called 'mouse', a little infra red emitter that you plug into the back of the recorder. You tell the machine what type of Sky Digibox you have. You're all set up.
You tell the calendar what program you want to record, and the channel. When the time comes, the 'mouse' transmits the signal to the digibox to switch to the appropriate channel.
Otherwise you can just use the Sky EPG 'Autoview' feature.