Hi niko - you can draw a construction line off of a surface normal. If you want to place more than just the 2nd point of a polyline on a surface normal then the easiest way is to start out by making a construction line along the surface normal initially before placing any points and then you will be able to snap as many points as you like on to that construction line.

Let me know if you are still stuck.

In order to make a construction line that follows the surface normal make sure you have not disabled the option for it under Options > Snaps > Straight snap options > "Surface normal snapping".

Also make sure you have "Straight Snap" enabled in the bottom toolbar (next to "Grid snap", and "Object snap") in order to get this kind of snap.

- Michael