You'll have to build a nightly yourself to accomplish this. After compiling the source, an update script is run that copies all appropriate files into an output directory. Within this script you'll see three commands of the form:
REM echo Stripping debug info from output tree
strip "%CB_OUTPUT_DIR%/*.exe"
strip "%CB_OUTPUT_DIR%/*.dll"
strip "%CB_OUTPUT_RESDIR_STRIP%/plugins/*.dll"
delete/comment out these commands.