Is it possible to use an old snap on mt 3500 cable( the brick) attached to the serial port on my laptop instead of the scanner to communicate with tunercats or winaldl or other programs

 

The Snap On cable will just get you the connector, you'd still need some sort of electrical interface box between the laptop and the Snap On cable. If you can get the pinout of the Snap On cable, it wouldn't be hard to build out "the rest of it" (I could do it if you're interested).

Cheers,

Andrew
http://www.akmcables.com