I am not offering to do this for you, but I have absolutely wondered MANY times over the years if this -- coaching highly technical people on writing better -- was a business model.
For individuals though, I think it's easy to see that the hourly rate can't be all that high.
For writing, the best bet is probably to get hooked up with some editor who does this on the side or maybe a writing prof at a local community college or adult education center.
For my part, I'm not exec level yet am in a position to use either disposable income or company money on coaching for skills such as writing.
My first thought too was looking for journalists/editors/local university lecturers who may be looking for some extra work. I'd guess that'd require trial and error for both parties.
My first choice would probably be to try to find an editor who does or would do this sort of thing as a side-gig. Maybe you have co-workers who have worked with one of the tech publishers like O'Reilly or Apress in the past who could do an introduction?