Sorry, I just stumbled in here and saw this. I have. My five times great-grandfather was at Yorktown. The information came from his pension application. Have you checked to see if you ancestor filed one?
I have the information of service with the PA Militia, (ancestor- Pvt. Jacob Hegie) who was a member of a Company that was in Yorktown, VA during that time. However, I wanted to know if there is a Yorktown list of those who were present during the months of the seige. Someone said that the College of William and Mary may have such a listing, but I am not sure.
I've never heard of any listing at W&M and don't know how they could have compiled it. You could try contacting them because it certainly wouldn't hurt to ask. Check the pension applications. The ones seeking the pensions often mentioned major battles and campaigns in which they served.