I have found a list of names and ranks of the 29 members of the Veteran Reserve Corp who escorted Lincoln remains to Springfield. These 29 men were the only ones allowed to move the coffin from place to place during the long funeral journey. However, I can find no criteria by which they were chosen. For the List of the 29 at the following web address Lincoln Discussion Symposium. Remark by RJNortonhttp://rogerjnorton.com/LincolnDiscussionSymposium/thread. 2136.html. Original list source from list source: Dr. Wayne Wesolowski.
That is all I have found thus far. Will keep looking.