Nurbs curves or polys?

If its polys then open the script editor and type

polyCreateFacet -ch on -tx 1 -s 1
-p X Y Z
-p X Y Z
-p X Y Z
;

Where the -p are the positions of the verts and the X Y Z are the positions of the verts in the relative axies.

Nurbs curves, open the script editor and type

curve -d 1
-p X Y Z
-p X Y Z
-p X Y Z
;

Again P = CV's, XYZ axies positions, this gives a liniar curve (sharp edges), if you want to change this change the degree of the curve (the value after the -d flag)