Just info for anyone wanting to do the same.
I created a circuit (with overheat protection as well as fused) that allows me to power the factory microphone inside my toyota tundra. basically have 4 wires for the car side... (+5v, GND, Mic+, Mic-) and on other side (Acc+, GND, Avic Mic cable) (for Mic cable just took apart my Mic and took the element off of it give me a 2.5mm cable).... so hook everything up and it works!!! well kinda... Avic is used to unpowered mic... so with this setup...a whisper is almost too loud... and when driving, the background noise is amplified so much that it's pointless to use.... I ordered an attenuator cable and going to try to make it work... (seems crazy to power a mic only to attenuate it... but it allows for a clean install and keeps my truck factory looking). I also tied into the factory XM antenna so I didn't need to put my own on it. the GPS antenna is under dash and works perfectly..... so only thing noticeable that I installed is my Radar Detector 
If anyone else is interested, then I'll post more details (after I confirm the ATT cable made it feasable to use).
-Rob