get a ninja or someone with Throw and a black mage or someone with at least lvl1 black magic, go to Jacole Cave (with the nut eaters and skull eaters)

when you get a skull eater, if you have steal, try to steal . . either elixirs or ethers from it, then hit it with black magic, it'll go bye bye then throw the tech/scroll on teh six in its place 8)

It's not necessarily the fastest way, but I love killing skulleaters because they gave me so much trouble the first time I played xD