Ehh, it's a bit hard to explain in a forum, but I'll give my best shot.
First, you need to make a perfect straight segment, around 20-30 meters long. Then press "I" to straighten it up. Now, break it up into 8 segments, each should be an even distance appart. Now highlight all of them, and press "I" again to straighten them up again.
Now, bank the segments like so (with the re-roll turned on for each segment): 0, 15, 35, 55, 75, 75, 55, 35, 15. Now you should have a perfect tracklined segment, with the heartline all wonky.
Now, highlight that element (make sure it's in another editor, all by itself) and double click on it to open up the individual segments settings. Now, check the "individual colors" box, and color the main track pure black (0,0,0). Leave the other color boxes alone.
Now save the element as whatever you like (i.e. heartline roll). Load the track up into the AHG and set the heartline you want (i.e. 1.1 for intamin hyper, 1.3 for floorless, 1.6 for standup -1.1 for intamin invert, ect.). Now load the track into the AHG, and set the number of segments you want to be (i.e. 15-20), and set your precision to about 6-8, and your filter to 100 for woodies, and about 300 for steels. The V-In and V-out is the speed of the train at the beginning of the segment, and the speed of the train after the segment. These will be measured in meters per second. You can find the calculator on NLDC in the coaster calculator section.
Now, after setting those, click heartline, and then save track (it should be automatically saved as (insert track name here)_AHG). Now load the track up and you should get your final product. You will have to tweak the bankings in the beginning and end of the segment to get the bankings exactly 0 degrees for both. The first node should have re-roll turned off.
It takes time. AHG will also not smooth out the tracks for you, but it will smooth the bankings, and properly bank the track for you, provided you set the speed values correctly. If any element has forces of 0.3 and below (i.e. airtime hill), you will need to color that element black to prevent the AHG from turning it into a roll.
I have an AHG tutorial on NLDC so you can take a look at that too.
Well, not really SFMMMan, you really have to do it yourself. Pretty much every element made in elementary is done all by you. Just a lot smoother the first time around.
And that was a joke, they are the true NL builders