How to generate help text at runtime for logging purposes

I'm trying to find a way to generate the help text (that would be displayed if the user asked for it) at runtime when there is a parsing error. We want to log this help text for console apps that run unattended during the night and where for some reason incorrect args were setup for the job.

I can see stuff like CommandLine.Texy.HelpText.RenderUsage and so on but I have no idea what these do and they don't seem to do what we need.

Many thnaks.