I did. I spliced into the mic at the TCU connector in the trunk (since I was running a video cable for the reverse camera from trunk to head unit anyway). In my case the mic was at pins 1(+) 19(-) of the 54 pin connector. (see below).
It worked for a few months -- and then died. Bad OEM mic? Bad splice? Short/open in the wiring somewhere? who knows? Rather than trying to fix it, I installed a new mic from Amazon in the OEM location and ran the wire directly to the head unit down the A Pillar (where I located the GPS antenna). I used hot glue to attach the mic to the overhead console (inside the console).
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
TCU-----------------------Combox
Pin---Description-----------Pin---Description
1----Mic(pos)--------------25----Mic(pos)
4----AUX-GND-------------10----AUX-GND
15---Crash Sig.-------------7----Crash Sig.
17---30 Power+ 5A---------2----30 Power+ 5A
18---30 Power+ 10A--------1----30 Power+ 10A
19---MIC(neg)------------12-----MIC(neg)
21---MIC Shield-----------11-----MIC Shield
23---Shield---------------22-----Shield
31---SOS sig.f Button-----18-----SOS sig.f Button
33---Wakeup-------------15-----Wakeup
36---31 GROUND(neg)-----14----31 GROUND(neg)
37---emerg. Speak.(pos)--21----emerg. Speak.(pos)
38---emerg. Speak.(neg)--20----emerg. Speak.(neg)
50---emerg. butt LED-----17----emerg. butt LED
54---GROUND-