Bob, I have often found that you can just add the turpentine (I use it
rather than thinner), mix in, then be sure to stir every time you use it.
If there's enough turps relative to the beeswax it'll stay unclumped.

That said, I've never done it on the stove.  I usually shave a measured
amount of wax into a quart jar, add the turps to make the wax purley
dissolved (letting it sit overnight is required), then add half that total
amount of blo, stir like hell for a while, and suddenly an English
facsimile of you is my mother's brother.

If it ever gets too thick, or clumps, I add a bit more turps.  The stuff
works a treat cleaning just about any tool wood.  I let it soak in for a
while on the (say) plane handle, then use 0000 steel wool to clean it up.
Wipe that gunge off with a clean rag, buff, and again, you're golden.

Bill
Felton, CA
just say it's probably time I mixed more of that stuff, I'm down to the
dregs of a quart jar.