In short: Tag an object as Caster in the Instance tab of the Converter with the object selected. Then export the .scn again. It will add the ShadowCaster=xyz section to the corresponding instances. Use "Textured" (sparingly) if you have an object that uses alpha blending and you want the shadow to be determined by the alpha blended texture, not the solid polys they're mapped to (also explained in the track technology v3 pdf).
Thanks for your help ethone, now I can see the sonbras of objects in the circuit. Another problem I have is how to insert the CornerWorkerAnims in the circuit. 1) After opening the project of CornerWorkerAnims, how do we export? 2) Once exported, did I have to add to the circuit? 2.1) If the answer is yes, How to insert it in the position I want in the circuit? 3) Do I have to re-export the entire circuit with the CornerWorkerAnims at once? thanks