Hmmmh, ofc technically you can. You just need to make sure you have enough effectivity vs regular hulls (which are thermal-resistant and kinetic-vulnerable). Incendiary MCs are mostly thermal, railguns are mostly thermal (but ofc do module damage) - I'd balance that out with some kinetic or absolute damage.
If you're good at short ranges -- i.e. getting close to an enemy and sticking there, preferably in his blind spot -- then Frags are also an excellent option. I've tried regular (gimballed) Frags for a while before I got the Pacs, and yeah they are fun.
As for
@Ceekay's build, I don't like that weapon layout at all -- if anything I'd assign the lasers and MCs exactly the other way round. Small MCs that aren't incendiary (for use against shields) or carry a rider just suck imho -- they only bring 22 Piercing to the table, which means that even with the Corrosive debuff you'll lose about 1/3 of your damage output to enemy armour hardness (against any reasonable combat ship). Usually I use a single small Hi-Cap MC to apply Corrosive and that's it.
If you want MCs and Rails and no lasers, I'd probably try the following:
L: class 3 MC, OC, Auto
MM: class 2MC, OC, Incendiary
M: class 2 Rail *
SS: class 1 Rail *
S: class 1 MC, HiCap, Corrosive
So you'd use the 2 med MCs against shields, the other 2 MCs against hull, and the Rails whenever you get a clear shot.
As for the <*>, the mods for the rails should probably be discussed separately. I'd take at least 1 Feedback Cascade, then maybe 1 SuperPen, or otherwise 2 Plasma Slugs.
But that's just a first draft, haven't simulated any of it in Coriolis or EDSY.