use comcast remote swap button to cycle between 3 channels instead of just 2

press the swap button pick a channel A
press swap button to return to the previous channel 
pick another channel from the guide B
pick a 3d channel from the guide C 

use the last button to cycle between B & C channels and the swap to goto channel A at anytime 

remember to press the swap button to  return to channel B or C whichever was active when you pressed the swap button