According to Porsche they have different part numbers for the 09 GTS and the 06 Turbo. Looks like you need a Tiptronic from a 04-06 Turbo. And it looks like the control unit changes on the later DFI cars, so that could create another issue, if you go that route. Best bet is to stick with the Turbo transmission from 04-06. Or go wild and put the PDK from an 2011 Panamera Turbo!! But...don't ask me how to do it
I bet that would be quite the conversion!
You could also try to find a (SUPER RARE) wrecked GTS with a Manual shift gearbox in it!! Buy the pedals shifter and gearbox with clutch and clutch actuation stuff and have at it