You seed your points as XYZ sets, so the number of points for the 'main' part of the line will be an array of sets of 3: the points on your main line will be indexes 0,1,2 for the first point, indexes 3,4,5 for the second point, indexes 6,7,8 for the third point. etc, etc.
The Justification is the side to offset by. acTop & acBottom are which "side" to offset your "main" line by: acZero basically offsets both lines from your imaginary line running down the middle of your points.
MLineScale controls the offset amount.
The sample code provided in the help, is not much help.
Take the sample code, erase all the points except those from index
0-8, and make them the following values:
0=0. 1=0. 2=0.
3=0. 4=-10. 5=0.
6=10. 7=-10. 8=0
This will basically make an "L" shape, unlike the overlapping crap that the sample source gives you.
Then play with the Justification and MLinScale properties; you should get the hang of it then.