How do I use the API to swap one sketch in a loft?

I have a loft feature in a part (in an assembly).  I would like to change one of the sketches defining the loft programmatically.  I'm not sure how to do this?   I found http://help.solidworks.com/2012/English/api/sldworksapi/create_loft_body_example_csharp.htm , but this seems to create a loft *body* from scratch, and I have a loft *feature* that already exists that I would like to modify.

I can't find any good documentation on this.  Has anyone done this before?

Valkyrie

SolidworksApi macros