I use a Bernzomatic mini torch (butane refillable kind) to melt a generous amount of black dop wax onto a flat dop (I cut the pavillion first). Of course everything needs to be super clean with alcohol. It definitely helps to have a flat spot on the stone to stick to the dop but not entirely neccesary. You can use an old tranfer jig to complete the process – keeping the stone still with a vee or flat dop on the other side, I gently heat the stone and the wax covered dop until the wax really starts to flow. I bring the wax-covered flat dop down onto the stone and then I get more aggressive with heat on the stone itself – hot enough that the wax melts onto the surface. The whole thing feels a lot like soldering gold. You know it’s good when it flows right. Then let it alone to cool.
There are A TON of caveats, and practice with that method will reduce burns, mishaps, and bad bonds somewhat, but a lot can go wrong with this method and you should be aware of the risks. It’s not precise (lower yields), it’s not for sensitive stones, and to get enough wax to support the stone usually means that you need to clean it up with a razor blade and you still end up chopping wax on the girdle facets BUT if you want to start cutting in 10 minutes or less, it can work. Coarse grits at high speeds can knock anything off, so be slow and gentle when beginning a new facet.
Last tip: if a wax to wax transfer ever works, it’s a miracle. I gave up on it years ago. Super glue makes me nervous on the transfer so I always make a wax “cushion” on my cone/vee dop and epoxy over the wax then let the transfer sit overnight. I know guys in the big leagues who would say that getting good with super glue is the only way to go but I’m rarely in a hurry after the transfer so epoxy works great for me.