I use Helpmaker 7.4.4 from Vizacc. It is not a brilliant program and rather idiosyncratic. I think vizacc agee as they seem to be in transition to a rewritten version Helpmaker IX but although they have screenshots of the new version on the site only version 7.4 seems to available for download. Don't be fooled by the link "Helpmaker IX CHM register", that's something different.