You don't even need modtweaker for that. I think, there is a modtweaker thing for this, but I never used modtweaker, so I can't help you with that way.
For the IC2-way, tThere's a how-to on how to do it in the IC2 jar file under assets/ic2/config/macerator.ini (just open the jar file in 7zip or winrar)
i believe crafttweaker support is not a thing anymore but if you want it you could try asking Jared for IC2 support he might do it. but as Aroma says you could do it his way.