interleaved C in .ptx

Hi all,
I’m using Visual Studio 2008 to compile CUDA programs. I’d like to be able to look at the .ptx file with interleaved C, but I’m not able to produce it.
I’v tryied with -ptx (tells me that ther’s an error because of a missing file), -keep (I’ve found the .ptx in the working directory) and any combination with --opencc-options -LIST:source=on.
But still … no interleaved C.
Is there something special I have to do? Where the .ptx file with interleaved C is supposed to be located?
many thanks