The way a firesteel works is that small particals of the firesteel alloy shaved off the firesteel. It takes a sharp edge some times. With a hacksaw blade there are two methods, 1) smap the saw blade with a pair of pliers so a jagged edge is formed where the blade breaks. Use this edge to strike against the firesteel. 2) Use the teeth of the hacksaw blade this produces tons of sparks but it will chew up the firesteel and leave it grooved.
I also use an old blade from a SAK using the sharp edge to make sparks.
But I think once you under stand how a firesteel works it is simple to make sparks.
cheers