ATC module: Added keyboard combinations for XPNDR selector(STBY, TA, TA/RA), now I need help to write the script!

Hi everyone! I'm Mattia, I've started a 737 home cockpit project about 2 months ago.
At the moment I've got 4 OC's modules:
MCP, FMC, EFIS and ATC.
I'm linking all the hardware to the PMDG 737 NG in FS2004.

I'm trying to find a way to link the ATC to the PMDG, in particular for the Mode selection (STBY, TA, TA/RA).

The difficult part was to create an event in FSUIPC to control the PMDG's XPNDR mode selector, since this function does not exist.
I've found a way to assing keyboard combinations to increase and decrease the selector using "mouse macros".
Pressing "I" it increases the selector, pressing "SHIFT+I" the selector decreases.
Actually these functions work very well, in fact I'm able to select XPNDR mode pressing the switches on the CH Throttle.

Now I want to add these functions to the OC's ATC module.
For example rotating right it should recall the keyboard button "I" (increase) and rotating left it should recall the combination "SHIFT+I" (decrease), just like the EFIS ND range selector. Exactly the same...

Unfortunately I've tried all I could with script files and SIOC.ini (I've got SIOC 37b1), but I wasn't able neither to see a changing variable rotating the ATC selector (I wonder if it really works or if it is a dummy!!!).

Can anyone help me to write a script in which I can assing the two combinations to the selectors?