Sorry, no advice....but that idea sounds fabulous. MMMMM, cashmere....good luck!
Do you have any patterns for pajama pants? You could just use that pattern and alter it for your shorts. Mmm, cashmere shorts. I made a scarf and mittens set out of an old cashmere sweater a couple months ago. My sister love them. Best of luck with your project!
kinda like that, but longer in the leg.
Maybe you can get some inspiration from this website : http://www.dab.hi-ho.ne.jp/runo/ht/howto01.html