Tried doing mods.refraction.AssemblyTable.addRecipe(name, extrautils2:ingredients, {minecraft:redstone,minecraft:redstone,minecraft:redstone,minecraft:redstone,extrautils2:endershard} , "16", "32", "255", "255", "0", "0", "0", "0")

but no idea what "name" stands for and wonder what is the correct way to insert numbers and inputs/outputs

Name is just whatever you want, that should probably be internalized to something along the lines of "mtrecipe{hash of ingredients}" so that we don't force the scriptmaker to know what that means @murapix

For future ref:
mods.refraction.AssemblyTable.addRecipe("name", minecraft:glowstone_dust, [minecraft:redstone,minecraft:gunpowder] , 16, 32, 255, 255, 0, 0, 0, 0);
Also modtweaker was required to do this.