you use Content Manager to search & download from the DLS in TS12. No need for coping & such. Things made for earlier versions (04, 09, 10, etc) should all work in 12. Some of the stuff older the 09 may have errors & not work, but most should work.
Also, if you only search for TS12 content on the Download Station, you may not find a lot, as most assets were created in earlier versions (Trainz Classics 1+2 or 3 are the common versions at the moment - trainz-build 2.7 and 2.8.