You can do it with a macro if you want it to be TV Input in every mode. But it's a little tricky. The macro key will be Input and the macro steps are TV, Setup-Input (I think).
If you only need it in TV and CBL mode, you can just do a key copy from TV Input to CBL Input.
Macro and key copy instructions should be in the manual. If not, see the How-To link in my sig.