I recently got a Carhartt cotton jacket and wanted to wax it.
16oz raw linseed oil (the "boiled" linseed oil isn't boiled, it just contains heavy metals like cobalt as a drying agent. Not what I want against my skin.)
Bowl or pot that you don't want to use again for food
Clothes iron you don't want to use for clothes again (a ski wax iron is great as it can go hotter)
Multimeter with thermocouple (optional)
Melt the beeswax in the bowl. Don't add the linseed oil yet.
Once the beeswax is melted, add the linseed oil.
Raise the temperature of the mix to about 150 C. I found this to be a good compromise between smoking and ease of application.
Coat the jacket with an even layer of wax/oil mix. Don't worry about it being pretty.
Once done, use the iron to melt the wax into the jacket. It should practically disappear into the fibers of the jacket.
Hang the jacket outside for a couple days for the linseed oil to dry.
That's it, you're done.
Things I found to not work:
Using a hairdryer to melt the wax into the jacket (too slow)
Using a heatgun (also too slow)