I usually set up a condensormic on a high boomstand in the recording studio in front of the controlroom's window. If someone tries to speak to you they will tend to look at you so that's why I set it up near the window. They'll be facing me and the mic. A omni mic in the midle of the room will do also. I route it to a spare channel on the mix, and whenever a musician wants to speak with me a level up that channel. I talk back through the haedphones of sometimes through the speakers in the recording room. Offcourse when a singer is recording I use his vocal mic, but for other musicians a have a talkback mic standing in the room.