In the spline modeller I believe you can also import .ai files to be used as the sweep path (in addition to cross sections). On the PC I save my paths as .ai version 8.0 and they seem to load fine. If all you need to do is draw curves, something inexpensive like XaraX (http://www.xara.com/products/xarax/) might suffice (I'm assuming that it can output in a format that Carrara can load although I haven't tried it). Like C4D, Carrara is nice in that your curves remain editable as you model. In Lightwave once you lay down a curve you can't easily go back and change it later.