I mean if you look at the commercial ones, you can see what basically needs to be done.
What you need:
A corning keg or 5 gallon keg, first make sure it will fit in your pot, if not find a cylindrical object that does.
3/8 inch food grade tubing, Here is what I got:
http://www.lowes.com/pd_4182-58421-D+06050PS_4294822004+4294763500_11_?productId=3427604&Ns=p_product_qty_sales_dollar|1&pl=1¤tURL=%2Fpl_38_4294822004%2B4294763500_11_%3FNs%3Dp_product_qty_sales_dollar%7C1&facetInfo=3/8
3/8 plastic tubing (drainage and inlet).
2 clamps
Then you just wrap the tubing around it I found the easiest way was to just put the whole roll around the corning keg, and then just pull the ends tight. At one end be careful when you bend it up towards the top, as to not get a crease in it, So to do that I suggest wrapping a hot cloth around the portion you are about to bend and bend it slowly. You wont get 90 degree angles.
Then cut the PVC tubing and clamp it to the inlet and outlet. They should both be at the top, The Inlet side should be the top of the coil, and the outlet should come from the bottom.
It will take all of about 10 min to make, once you have the parts