Hi,
I came across your post, which came up first when searching for "set printf_support", when searching for the same problem. I know this is an old post but it may help others.
It's there; we just missed it. Go to Project > Properties then navigate to Build > MSP430 Compiler > Advanced Options > Library Function Assumptions. It's the first item above the check boxes. Click the drop-down list button to select your option (blank, no float, minimal, full).
Hope this helps others.
Ed