I'm not quite sure if I have those chapters, but if you click on the link in my signature, it'll link you to a page with manga, and if you look for Black Cat, there should be a link that says Vol 20+gaidens (I believe) and if you click on the sendspace link, you could try downloading it, see if it has the files you want. Because I believe I DO have those sidestories...just need to find them.
Anyway, try the link first, if it doesn't work, reply and I'll see if I can dig it up. xD
"What I know...has got nothing to do with you." -Bleach, ch 239