Another answer and a method relatively overlooked here in the uk this could be done would be using a smart splitter and an scr single cable router compatible lnb or satellite multi switch amplifier and scr enables satellite receiver the majority of new sky hd boxes come equipped with this facility accessed within the hidden installer menu.
Sky hd satellite cable splitter.
A seperate cable from the lnb is the only sensible option you should have two spare outputs if you only have one sky sky hd box.
If you are looking at extending the wires from your satellite dish to your sky box then a sky extension cable is what you need to get the job done quickly and easily.
A switch will connect one or the other and not both at once.
Make offer triax 2 way splitter 5 1000 mhz 347012 hts2 dc satellite tv cable sky and virgin technetix esx 03 3 way splitter 5 1218 mhz quality sky virgin media catv x2 3 00 1d 18h.
If you look the splitter passes dc back from both outputs to the input.
Search no more for an awesome satellite tv splitter as this brilliant satellite tv splitter supports a number of different hdcp inputs such as 1 2 1 1 and 1 0 plus it also supports hdmi 1 3 making it truly exquisite and exceptional in transferring a number of different video formats such as 1080p 1080i 720p 576p 480p 576i and 480i.