I understand that you want to confirm how the Slingbox PRO-HD works, if you are going to be able to have different channels when you are connected to the Slingbox and at home using a TV. You have two options to do this:
1. You can connect the Slingbox to a dual tuner device like a DVR; at home the TV will be controlled using RF (ratio frequency) and the Slingbox will always work with IR (Infrared). In this way, you can have different channels at home and the Slingbox
2. Using a coaxial splitter on the signal coming from the wall; one end will be used for the Slingbox and the other to the Set-Top box.
Have a look at this thread, you will find more information about this:
Hope this helps.