Turnkey with wireless connection.

But in practice it will be a struggle. Basically what you'll need to do is download the deb packages required (and any missing dependancies - from another internet connected machine) and manually install them on your TKL system. You'll need lots of patience and probably a bit of back and forth with a USB stick. If you are unfamilar with Linux then you'll probably want to also read about mounting USB devices from the commandline. It may also be possible via Webmin but I am not familar with it so can't offer much help there.

If you are willing to commit the time and energy I am sure you could get it to work, just depends how bad you want it! :)

If you keep in mind that TKL v11.x appliances are based on Ubuntu 10.04 then you will find plenty of relevant info via google and/or the Ubuntu forums and docs.

Yes... but, I don't have a LAN-connection, ONLY WiFi. 
I don't have onboard LAN.

Take a look at this thread. You also might find my crib notes (last comment) useful.