Right now, the MAXScript splineShape methods only accept a node which means that as soon as there's a modifier applied, you can't use them. You can't use them with the simpleSpline scripted primitives either where they'd be a natural fit if they'd accept the bezierShape parameter. Right now, simpleSpline is the only good option for parametric scripted shapes as shape plugins using the extend syntax result in buggy rollout duplication (see Scripted Shape Plug-ins adds unnecessary rollouts).
