I was looking through Kenneth Huff's Siggraph presentation. Though he used maya, I think the same principles would work in Cinema4d.
From the website:
The basic curve for the knot form is based on data I download from the Knot Server at the Knot Plot web site (http://www.pims.math.ca/knotplot/) (www.pims.math.ca/knotplot/KnotServer (http://www.pims.math.ca/knotplot/KnotServer/)). The Knot Server provides a sequence of three-dimensional coordinates representing a given knot. In the case of the 98 knot, the sequence was:
4.027354 -0.973963 -0.733554
3.542408 -1.555169 -1.754737
5.224526 0.644712 0.772574
4.595191 -0.275349 0.169248
To convert this sequence of numbers (91 coordinates in all) into a curve in Maya, I used a text editor to change the list into a MEL command:
curve -degree 3 -name "knotCurve_9_8"
-point 4.027354 -0.973963 -0.733554
-point 3.542408 -1.555169 -1.754737
-point 5.224526 0.644712 0.772574
-point 4.595191 -0.275349 0.169248 ;
I modified the resulting curve in Maya in order to increase the overall three-dimensional volume and the intra-curve spaces, thereby maximizing the size of the tube cross section which can be used.
After a simple extrusion, using a circular profile, the resulting knot form can been seen here.
Could I do this in Cinema 4d? I would prefer to use this method over the 'export to .dxf' option since that always seems to bring in clunky and large objects.