Julia - are you sure we're not twins, lol?!? When I made that pair of longies, it called for DPNs and I just didn't think I could handle it, so I taught myself Magic Loop using this website:
http://www.az.com/~andrade/knit/mloop.html
It only took me a couple of minutes to figure out, but it was really slow going for the first dozen rows or so. I actually was thinking that I didn't like it in the beginning, and went out and found some DPNs, but I gave it another try and now I love it! I use the DPNs for I-Cord, but I use the Magic Loop method for everything else. The hat pattern and longies (LTK) both called for DPNs but I just used Magic Loop.
Basically, when you are supposed to transfer to DPNs, you would transfer the stitches to the same size circs, but with a longer cord (you're probably using size 7s in 16" for LTK; you'd need size 7 circs in 29 or 40" for Magic Loop - I used 29" with no problems). Once you have them on, push all stitches to the center of the cord. Count to the center and pinch the cord in the center and seperate half the stitches onto one needle and the other half on to the other needle (just hold the cord/needles together and slide the stitches to the needles. Keep the needle with the yarn attached in back. Slide the stitches on the back needle to the cord and knit the stitches on the front needle. WHen you've finished knitting those, you turn your soaker and slide the stitches on the back needle to the cord and those for the front needle to the needle and knit. Every 2 times, you've completed a row. One thing I learned hald way through my first leg, is to be sure to pull that first stitch fairly tight every time or you will end up with a big gap between the stitches (supposedly it's easy to tighten them up, but I couldn't do it, and when I started to pull that first stitch tighter on the second leg, I didn't have that problem at all.)
there is another option, and that's to get 12" circs to use for the legs. I had asked about them here and someone said they would still be too long to use, but a few days ago someone posted about doing their legs successfully with them.
will write more in a bit, it's lightning really bad here!