Build yourself a nice campfire w/ logs about the thickness you would for a fireplace. Then get the campfire nice a hot, get yourself a nice 1" + Layer of coals on the bottom.
Then place the knife on the coals, attach the knife to a coat hanger so you can pull it out after it heats up. Build a smaller "indian type" structure w/ 1.5"-3" logs/thick branches OVER the knife on the coals. Let it sit for about 15-20 mins. It will get VERY hot. You can actually melt the steel in a simple campfire a/ a good bed of coals, so be careful. The color of the steel turns from light red, to a deep orange, and can go all the way up to a bright yellow. This is what we want to avoid, the bright yellow & a campfire can take 1/8 steel there easily. Just keep your eye on it, and pull it out every 5 mins or so, and check the color of the steel. You want the deep red/just before orangeish color before you quench the blade. Quench the blade in regular vegetable oil. Let the vegetable oil sit next to the fire from beginning to finish, this will heat up the oil so when you stick the red/hot blade in there, it won't stress the steel too much by hitting something cold too quickly. You can get a thermometer & all that to test the temp of the oil, but don't worry about that. Just as long as the vegtable oil is umcomfortable for your finger to stay in for more than 5-10 seconds, then it's warm enough to accept the hot steel for your quench. Pull the knife, AT DESIRED COLOR out of the fire and immediately dunk it in the oil. Make sure you get all the blade part in, I like to leave the handle red hot while the blade sits in the oil and cools immediately. This is a form of differential treating.
You can do it all in a simple campfire & small pot of regular vegetable oil. Pay attention to the colors of the steel as your heating it up & after 20-25 mins quench it.
I like to let my steel bask in the heat for alot longer, this is called soaking the steel, but in a pinch, it isn't vital to making a good blade if you don't know what you're doing.
