I use the iron with the steam on for this, as it helps get the wax down into the fabric. The steam going down and OUT keeps the wax "fumes" from going Up and Into the iron. Again, Its not been a problem for me in actual practice.
I did this years ago when I was trying to waterproof something- I don't even remember what it was, now. Possibly, Some kind of cover for gear in camp. Dad had given me a chunk of Beeswax, so I melted down some , and used a paint brush to spread on the fabric. The steam iron was then used, with the fabric sandwiched between the iron and some paper towels, to spread the wax evenly. We checked the Iron after the first stroke, because I didn't want the iron picking the wax up off the cloth, rather than melting it and driving it into the fabric. I used an old iron I had bought when I lived in an apartment during college and law school.
Years later, I used paper towels and a steam iron to lift candle wax off a dining room table that had a varnish finish that would have been ruined if I tried to scrape the wax off the finish. The wax melted and was soaked right up into the paper towels. A couple of repetitions, and the table looked like new.