yes, on your macro you will have an if/then option.

first you add the voltage sensor as a device, and assign it to a port on your nevoconnect. 

then you create an if/then/else statement. 

so for your Cable TV command, you would do :   if cable box power is off, then send "Cable Pwr" 

for an all off command, part of it would be  :  if cable box power is on, then send "Cable Pwr"

here is a file I did a while ago that has if/then statements.   I am using a voltage sensor in this setup, but it would be similar to what you need to do.

[Link: remotecentral.com]