Hi Josep,

I am not familiar with the slingbox but still may be able to help. When u say the Sling box has IR Control too, do you mean it has its own IR remote control?
It sounds like you are trying to control your homes X-10 lights/appliances with the same remote as you control the slingbox. Is that correct?

If both of these answers are yes, then it seems to me that you simply need a remote which can learn the slingboxes IR commands PLUS one which supports X-10 commands. I may be able to help you with that if my assumptions are right. Let me know.