Aceton works fine. Clean die, inside ihs, outside ihs and pot carefully with aceton. Then apply a big blob of kryonaut on die. Mount ihs, put some kryonaut on ihs and mount pot (I mount very tight but not sure it is actually needed). I have never had a single crack this way. No need to heat up or cool down in a special way. Just pour.
You can reuse the kryonaut on the die if you don't remove the ihs. I tried it and could do 5-6 sessions, but eventually it will crack. So I redo it every time just to be sure...