Use setowner.exe from NTSEC utilities
setowner -r -addpriv <domain\username> <path>
-r is for recursion into subdirectories and files in them
-addpriv allows granting of permission to the specified user
Use subinacl.exe from w2k resource kit
1. To set ownership of file(s)
subinacl /file <filepath> /setowner=domain\username
eg.
subinacl /file c:\temp\test.txt /setowner=CONTOSO\John
2. To set ownership of folder tree
subinacl /subdirectories <folder_path> /setowner=domain\username
eg.
subinacl /subdirectories c:\temp\l1\ /setowner=CONTOSO\John
subincal /subdirectories c:\temp\l1\* /setowner=CONTOSO\John