I use a 'mutton tallow / paraffin / beeswax' mix as a under bullet lubricant in my muzzle loading revolvers.
I bought an old crock pot at a yard sale and put a pound of each in it and heated it for a few hours then ladled it into canning jars. It is probably the easiest way to mix them instead of melting over a double boiler and all that this is no risk. For the revolvers I cut a tiny chunk out and work in my fingers a few seconds to soften and then roll into a tiny ball and flatten it.
If you put your tallow and beeswax in an old crock pot you could probably essentially do the same. Make a mix that works for you and jar it and then dig some out and just rubbing it in would probably generate the heat, as Pat B said, to work it into the wood