Is there a way to prevent svcutil from implementing IExtensibleDataObject?

Question

I'm trying to create a Portable Class Library. It will support .Net 4.51 & Windows Store apps.

For some reason the option to Generate Task-Based Operations is disabled. Yet both .Net 4.51 & WIndows Store apps support this.

There is a connect issue open as will not resolve and the work around doesn't work or isn't something we would want if it did.

Questions 1) Is there a svcutil for Windows Store Apps? (Add Service Reference from a Windows STore app and trying to shoehorn it into a PCL isn't what we're looking for.)

2) Is there a way to prevent svcutil from implementing IExtensibleDataObject?

Thanks