Cast3D itself is transparent and not dependent on any type of coordinate system, but the reeding engine is! Both Sandy3D and Papervision3D use left hand side coordinate system. So porting code of Cast3D for those is also left hand.
Most of 3D modeling tools use Right hand side coordinate system. which means any file with 3D data would need conversion from Right to Left system.
I you use Cast3D (.3ds) file utility for importing 3D models it does it by default, although there is an option to disable system flipping.