I found this to be the easiest way to align object orientation along a curve. Using pointOnCurve command, you can query the position, tangent, and normal information. Using normal and tangent vector, find the bi normal / cross product and arrange all the numbers in a translation matrix with xform command. Normalized everything except position.
 | Finding the cross product Mel or python has the "cross product" command, but to do it manually, you can do this: Given the normal { Nx, Ny, Nz } and tangent {Tx, Ty, Tz} binormal = Ny*Tz - Nz*Ty , Nz*Tx - Nx*Tz, Nx*Ty - Ny*TX Prevent the normal from "roll" around the curve Specify the "up vector" for the curve. For example, Y can be up vector. Using this information, find the normal by calculating the cross product between tangent and the up vector. Given the up vector { Ux, Uy, Uz } and tangent {Tx, Ty, Tz} normal = Uy*Tz - Uz*Ty , Uz*Tx - Ux*Tz, Ux*Ty - Uy*TX |