Open the MSP file (in your case it may be named as cos002a1001_msp.nii) in an image-editing tool (ITKSNAP or FSLVIEW), where you can draw and save a segmentation. My preference is ITKSNAP.

Draw the CC manually on the the MSP image and save the segmentation as a file cos002a1001_cc_corrected.nii (This corrected image should be a binary image)

Now you can run the yuki with -cc option as follows:

yuki -ppm -cc cos002a1001_cc_corrected.nii -i cos002a1001.nii -csv cos002a1001_corrected.csv -H

The important option here is the -cc option that you should use to mention the corrected binary CC image.