Yeah, it's easy. Corrugated cardboard, cut to about 2/3rds the height of the can. Tightly roll the cardboard and slide into the can, corrugation running vertically. Melt your wax and poor onto the cardboard, allowing it to soak up to about 1/2" from top of cardboard. The whole thing burns like a giant wick. You should see a blue flame settle on top of the cardboard.
You'll have to play with this a bit. If the cardboard is too close to the top of the can, it will flame up and become a fire hazard. To low, and it won't have enough oxygen to burn.
Also, when you blow it out, toss it out of the tent. You wouldn't believe how much smoke those things can make.

Make sure your tent has some ventilation so you don't asphyxiate yourself.