this is the completed thingie. it's a bit big for me. i think i shrunk since i stopped working, but if the pants fit you right, it will be a lot shorter. (blush)
it was surprisingly easy to make too. you start with old pair of pants and then cut across above the crotch area. (it may be best to pin up the pockets as in the photo so you won't cut off the bottom as i did and need to sew it back up) so now you have a really really short skirt.
then i took the legs of the pants and cut them up into kinda square shaped pieces. i found that i really liked the jaggedness and texture of the pieces from the seams, so i didn't do anything to them before attaching with pins in a haphazard manner. but if you'd like a more neat and uniform look you could use pieces just from the straight of the leg and hem on three sides before sewing to the skirt in a nice overlaying pile of flesh. (there is lots more leg to the pants than you need) i'm pretty sure you could cut bigger and longer pieces too if short short skirts don't float your boat. but i'm not sure how would be best to add a second layer though. (otherwise i might have done it)
and then i just ran it through the sewing machine (keep pockets pinned up so they don't get sewed in!) and it was done. this took a little less than an hour to do and made me feel super nifty and adorable when i was done.