VicoVR v1.1 SDK should contain RoomHMD example with T-pose detection and calibration (viewtopic.php?f=2&t=3
Currently in our demos we do it like this:
1) we get head, torso, shoulders, elbows and wrists joints from skeletonData. Check their confidence (should be greater then 0.5). And then check if arms joints lie approximately on same line ( Vector3.Angle (handsDiff, handsDiff[i]) < angleDiffTreshold (handsDiff here is the difference between wrists, handsDiff[i] - differences between nearby arms joints (leftWrist - leftElbow - leftShoulder - rightShoulder - rightElbow - rightWrist) ) ). If all conditions are met we save positions of those joints.
2) then for some time (~1 - 2 sec) we check joints confidences and positions (should be approximately in same place as they were).