I listen to them everyday, just program the 400 MHz frequencies that are in the database and you will hear KYW and fox regularly. They actually share the Choppers between the two Networks, last I had heard Channel 6 was on a communication system called sunshine Communications, never bothered with it myself.
The two most important frequencies to be listening to are 135.875 and 135.975, these are the air to air frequencies used by news media across the country, Philly uses Channel 1 and New York when they come down to visit will be on channel 2 but will switch over.
You also want to be listening to 126.900. That's Northeast Philly Tower. Some news Choppers take off from there and some take off from Penn's Landing but you can follow them on 123.025 also, that's Unicom for helicopters in the Philadelphia area, sort of a collision avoidance system, all Choppers announce their location and intentions on this frequency. Private carriers, medivac, police and news Choppers.