You will most likely have to take the entire turbo assembly off the car. It's not too bad though.

As for the wastegate flapper, just remove it. It is one bolt and the flapper is out of there. Then port the HELL out of the hole. It should be as big as you can get it. The turbine housing on my Green is just a stock housing that had the flapper removed and the hole plugged where the flapper arm went through. (You will need to plug the hole where the flapper arm was. You will have to have a machine shop weld a plug because it is near impossible to tap into that stuff. It will be very cheap though.)