Well i just make an S shape on nolimits using only one section of track. It also has to be exactly flat. Then when you've got the base to be the exact size you want it, you split the segment, so it becomes to pieces. Then click on the middle joint (i hope you get what i mean) and raise it up to the hight you want it. Be careful to keep the height change realistic for the sixe of the corkscrew. Then you start banking the corkscrew, bank the middle joint to an angle of 180 degrees, and on the last joint, you press re roll, and then bank that another 180 degrees. Now you should have the "base" shape for your corkscrew. Now you have to make it smooth, so start by locking the control points on the middle joint. Make it to your desired shape (i hope you understand whta i mean). This will amke it more of a corkscrew shape. Now you press Con roll, on the middle joint, and the other joints that make up the corkscrew. You should still only have 2 sections of track that make up the element. Now you split each section that makes up the element so you are left with 4 sections in total and 5 joints. Bank joints 2 and 4 each way, so this means the top 2 sections of the corkscrew bank faster (i hope you are still with me!) Then click on Con roll for all joints!
I really hope you understand that. Im not very good at explaining. After practicing this technique it makes a smooth corkscrew, wingover, or barrel roll (depending on the shape and size you made your S at the beginning). It will make the element smooth, but NOT heartlined. It is very hard to make an element heartlined, especially a corkscrew, without using a tool.
I hope you understand what i mean. Let me know if you dont!
EDIT: Crap, Kev, you got there before me!