So, here is my solution for mounting a Dremel power tool on the tool post of the metal lathe.
It is very usefull for all kinds of works, I use it for milling longitudinal grooves on metal, but also for grinding all kinds of materials that are difficult to cut like for making mother of pearl or abalone dots (I glue a piece of raw MOP at the tip of a wooden dowel, and install it in the lathe, turn slowly and grind the pripheral with the dremel in the tool post).
It is a standard M20 nut, welded at the tip of a 12mmx12mm square steel bar.
M20 works fine for the Dremel and similar high speed grinders (at least in Europe, I couldn't swear for the US)
First possibility : install it in the tool post, just like a lathe tool. It can be used to grind longitudinally or transversally.
Other possibility : installed in the vise of a milling square (I don't know if it's the correct name for that adaptation that allows to perform some milling work on the lathe).
In that last case, you gain a Z axis and it allows to setup the cutting depth.
Here it is !