Start at DAR.org - click ancestor.Enter Daniel McCoy.
This will bring you to his DAR record. On that you can find his descendants names who submitted the record and the DAR chapter that where they registered at in PA as follows: Wetzel, Estelle Lytle McCoyChapter: 2030PA Normecutt, Carrie Henry Chapter: 2100PA You might start by checking with those local chapters for information. Or just start with the data/decendants listed to begin your search.
There are many excellent sites that contain information on the PA regiments that participated in the Civil War.
Here's one that you can begin with, althought I am sure if you search on google you will find more.