The T1 to FT-817 cable contains one of Wayne's famous microcontrollers.
As far as I know they don't have a T1 to K3 cable, but they did document the protocol.
At least one enterprising ham has built an interface for it:
http://blog.zensunni.org/electronics/arduino-elecraft-t1-interface/You could fairly easily adapt this design to connect via RS232 to the K3 and request its current band.
Leigh/WA5ZNU