There are lots of pins left on the PIC processor, you could add code to output the needed controls to them. Having RC6 and 7 as a tuning status register would be easy. Set RC6 to high when tuning. Set RC7 high when in auto mode....
These status pins could be sent to an arduino for further processing...
You will need a C compiler to requild a hex but at least all of the source is there. I have not built this code to confirm that the free compiler for MPLAB x IDE works but I expect it will.
Colin Kaminski