See title. Already tried this: https://maymay.net/blog/2013/12/26/one-minute-mac-tip-open-multiple-tor-circuits-in-the-new-torbrowserbundle-3-5-for-mac-os-x/. Am I missing something obvious?
Check the Torify project. This support to route all traffic of a PC through Tor?
If you want to be sure there are no leaks, IMO the best way would be to connect it to a TOR Router.