how to create a custom skin in jCarousel
OK, after a moment of googling, I can say that apparently you cannot go without writing a tiny module, but even though I myself have been reluctant to write YABM (Yet Another... Module), it took me about 5 minutes.
Have a glimpse at this article, copy and paste the code, change the skin name occurrences and there you go - your skin recognized with clean hands. Thanks to http://timonweb.com.