Which version of Chemstation are you working with? Is it an older HP system or Agilent?

I think the problem here is that how one goes about "Data Processing" is highly dependent upon what you're trying to accomplish. I would presume that the user isn't wanting an old software manual (more than likely LabX could easily solve that issue). I If the user can define what they are trying to accomplish, you'll likely find folks with the answer.

The other point, is that depending upon what that is, the "How-to" may not be particularly straight forward. A colleague and I were once charged in writing a fully detailed SOP on running pesticides (EPA method 8081) on a GC. It needed to cover, instrument conditions, (not too hard), supplies (not too hard), QC (a bit cumbersome, but still do-able), instrument setup and maintenance (also a bit cumbersome), and then data reduction.

By the time the thing was done, we did not have an SOP, but a manuscript, right around 100 pages.

So, depending upon, what is actually being asked, the ease of an answer may be challenging.