The only way to do this is through a match. You could do a double match to OW/ST and then back to TK, but being TK*G wouldn't solve the easy spending of the miles.
If you are a true frequent flyer, choose a program, and write to them showing your flying history with ET, they might offer you a challenge (i.e. fly X flights with us and we give you *G). But to do this you have to fly a lot and in premium cabins, in other words you need to be a well paying customer.
Analyse your flying pattern and see if you can quickly earn *G somewhere else, you might have to endure a couple of flights without status but hey.