Yep, for some inexplicable reason, the AC and DC Commander omitted the chuff input and put a duplicate antenna connection instead, so I just solder to the R2LC socket to input the chuff.
FWIW, the Super-Chuffer II doesn't generate the chuff, that's an input to the Super-Chuffer II. If you need to generate a chuff, that's the job of the Chuff-Generator. The chuff signal (ground referenced) is sent to the R2LC and Super-Chuffer.