It is as simple as plugging in an HDMI cable to the video out. The MX300 G2 should start using the second display when you try to send presentation content, but you might have to change the following settings in the MX300 G2 yourself if it doesn't.
Congiuration Video Monitors: DualPresentationOnly
As for TMS, it doesn't matter in this regard, but what version of TMS are you using?