That procedure does not work, you will not get the double blink in step 3.The manual states
Locking Channel Control to CBL/SAT
1. On the remote control, press CBL/SAT once; it will blink
once. Press and hold SETUP until the CBL/SAT key blinks
twice.
2. Enter 9 7 3.The CBL/SAT key will blink twice.
3. Press CH+ once. The CBL/SAT key will blink twice.
Now, regardless of what mode you select (except AUD), the
channel keys will only change channels on your set-top box.
Locking Channel Control to CBL/SAT
1. On the remote control, press CBL/SAT once; it will blink
once. Press and hold SETUP until the CBL/SAT key blinks
twice.
2. Enter 9 7 3.The CBL/SAT key will blink twice.
3. Press CH+ once. The CBL/SAT key will blink once
4. Press any Device key
That device key will blink twice.
Now, regardless of what mode you select, the device you pressed in step 4 will be used to change channels.