Thanks for the lead. Surprisingly, I located the full set of the Supplement to the OR here in Oklahoma at library of the Okalhoma Historical Center. So, I went down to look up Dr. Hunter's report.

Well, I think I need an index for the indexes; there are 5 main index volumes and a few other sub-index volumes within the main compendium. I didn't find any specific reference to Dr. John Anderson Hunter but, there were hundreds of references by Series/page to "Charleston, WV", "Casualties", and "Medical"; I'm guessing that, if Dr. Hunter's report is in there, it would probably be one of these. But, it's going to take days to dig through all these entries.

I've found searchable web sites for the Official Records but not these Supplemental Volumes. I see that there are CDs with these volumes for sale on the internet; if they are searchable by key word, maybe that's the way to go.