I added several icons to show basically how it looks. These icons are 114x76 and I added a slight bevel in photoshop. I found these icons by randomly searching for TV Channel Icons on google. You can see here that there really isn't enough spacing, so in this case it would be better to make the icons a little smaller:
The next picture is a couple of shots from a job I did a while back. This is an example of how you can create a button to choose your zone. These icons are larger at 150x105. You can see they are really too large, as they take up more than one row of buttons on the remote. Here I created a combined button on the top and bottom row of virtual buttons, while the middle row is blank:
Just a couple quick examples and sorry for the poor iPhone shots.