Keep comments in preprocessor i file

We want to use the preprocessor output file (.i file ) for further use, especially the comments.
For that, we use the /PREPRINT (or /PP) command line switch.
The problem is that the KEIL compiler (C166) deletes any comments.

Q: Is it possible to keep comments in the .i file?

Additional research:
The Microsoft compiler does this with the /P command line switch.
But they has /C to keep comments.