The model wont animate beacause the model would be a biped and Irrlitch does not supports biped , it only supports bone animation, so do some trial bone animation and try , it will animate
This is correct , Irrlitch only supports bone animation so you cannot use the biped animation of max , rather use a bone animation and than use any exporter (i would suggest Panda for DirectX) to convert the max file to .X file format and Irrlitch will read the details automatically.