Passing #defines in as build options

I would like to pass some compile time constants in as build options:

eg:  "-D BUFFER_SIZE=512"

and then I would like to declare the following variable in my kernel:

local buffer[BUFFER_SIZE]; 

When I try this, (visual studio 2012) I get errors. Is there a way of doing this with the intel SDK and 

visual studio integration?

Thanks!