A user with administrator access can use the icacls or SetACL commands to set the owner of files.
You could use Opus to extract the author information for each file path, either by using the Rename scripting support (which should let you write a script which called icacls or SetACL directly) or by displaying the data in a folder and then using the Print Folder command to turn the listing into a text file which was then processed into a batch file.
I can't think of an easier way than those two methods.
Of course, it'll also be more complicated if you need to do some processing on the author names, e.g. if they do not exactly match the account names.