You can either run a cable from the RF2 output at rear of digibox to your bedroom, and use a TVLink to change channels from bedroom. Or you could get a wireless video sender which consists of a transmitter and a receiver. Using the latter method is handy, provided bedroom isn't too far away from the digibox (too many walls between transmitter and receiver can kill the signal).
If you have a Quad LNB (4 connections on the satellite dish) then you just need to run a cable from the dish to the bed room and connect up a second hand sky digibox....
you will have a Quad LNB if you have SKY+, if not you may need to buy one for about €40.... its very simple to fit if your dish is accessible...