I was determined to figure this out. And I think I have. I combined some expertise from Wippell and from my mother-in-law, who has a lifetime of experience starching uniforms for a Senior Chief Petty Officer in the US Navy (aka my father-in-law). Here's my method:
Step 1: I wash my collars by hand in the sink. You can wash them with the whites in the regular laundry. But this way I can wash and starch them all in one fell swoop. I use a small brush to give them a quick scrub as well. And I use OxyClean or some other oxygen bleach based detergent -- as clorine bleach will eventually cause them to yellow.
Step 2: Next I use some bluing to make 'em superwhite. PROCEED WITH CAUTION HERE. This stuff will dye your collars blue in no time. So follow the instructions to the letter, and make sure you're following the 'tub rinse' instructions.
These collars were in the diluted-and-then-mixed bluing rinse for no more than 5-7 minutes. And then rinsed and rinsed, and then rinsed again. Even if you leave them in too long, repeated rinsing will probably get the bluing out of them. Once you're done rinsing, wring them out and set them aside.
Step 3: Next it's time to mix up the starch! I follow the instructions on the package for Heavy Starch -- with a few emendations. I add a bit more powdered starch (a couple of tablespoons more) and a bit less water (about a cup less) to make the starch mix as starchy as I can. You'll want to follow the rest of these instructions carefully though; adding first some cold water and then boiling water. Don't add the boiling water directly to the powdered starch, it'll just clump up.
I mix the starch in a plastic container, and then store the mixture in the refrigerator for the next time. A batch will last a few months. (Update: Well, it'll last several weeks at least. After a while, it will sour. So, keep it well refrigerated!)

Step 4: Soak the collars in the starch for about 10 or 15 minutes. This is a batch of liquid starch from a few weeks back that I've taken out of the fridge and brought to a boil on the stove. You want to put the collars in the starch when the starch is -- not actually boiling exactly -- but still hot. Notice how milkly white the mixture is. That's because it's got a higher starch to water ratio than the instructions recommend.

Step 5: Once you've taken the collars from the liquid starch let them cool for a few minutes. Then remove the excess starch with your fingers. Be sure to let them cool first. And wash those tongs really carefully when you're done. Denton hates starchy tongs.
Step 6: Then lay the collars flat on a smooth surface to dry. You'll want to smooth them out with your hands, working from the center outward. You'll squeeze out a bit more starch when you do this. Dry this up by dabbing with a paper towel. You can lay the collars out on anything, I suppose. I've heard that the toilet tank lid works well! This is the discarded glass door from an old stereo cabinet that we found in our apartment when we moved in.

Step 7: Leave the collars to dry overnight.
Important Update:
After some trial and error, I realized that if you leave the collars to dry completely, there's no need to iron them. In fact, they're better off dried and un-ironed. They stay stiffer for a longer period of time (no indecorous comments, please) if they're un-ironed. BTW, putting your sheet of glass, cookie sheet, drying surface of whatever kind on your good, old fashioned, hot-as-hell New York City radiator and they'll be dry in a couple of hours!

Updated Step 8: Once the collars are completely dry, peal them off the drying surface, and fold them along the seam.
Updated Step 9: Then store your collars in your Wippell collar box to keep them nice and round over the next couple of weeks. Or...
Store them in the alternate collar box aka a Chinese food container from Grand Szechuan on Ninth Avenue.
Three starched collars usually last me for two weeks or so (even with wearing them while riding my bike to and from work!) After the first wearing, they have that sort of Titus Presler je-ne-sais-quoi wrinkled look.
I'd say this whole process takes about half an hour to wash and starch -- and a few hours on the radiator, or overnight to dry. I don't mind it at all as -- as many of you know -- it's the one thing I do in the kitchen in the course of two or three weeks. And yes, I thank God for Denton Stargel every day.
And the big pay off is that cloth collars are so, so much more comfortable than plastic ones (which for some reason turn yellow on me...) So, at least for now, I'm a home-starching cloth collar-wearing Old Skool priest.