in all my using of infernape in 4th and 5th gen, as well as testing out a banded variation in 6th, LO mix-nape is the way to go with this guy. infernape has great coverage moves on his special side, and with the equal atk and sp. atk base stats it's a sin imo to waste it for just physical attack. anyway, here's the set i use:
Dingo (M) Infernape @ Life Orb
Ability: Iron Fist
168 Atk/88 SpAtk/252 Spd
-Fire Blast/Overheat
-Close Combat
-Thunder Punch
-Hidden Power (Grass)
in my eyes, flare blitz is pretty awful on infernape, especially paired w/ life orb. it has such dire hp and defenses and talonflame or mega 'zard-X are more preferred users of it. overheat is nice since it packs more of a devastating punch on any pokemon that doesn't resist it, and even pokemon who resist it don't take it too well either! but fire blast does indeed have the benefit of not lowering sp. atk, so that's what i usually go with when i couple it w/ my mega zard-Y. close combat is essential, duh. as for thunder punch, i think it's a great coverage move on nape, personally. sure, stone edge is better in terms of coverage and bp, but i think when coupled w/ iron fist it does near close to the amount of damage s-edge does, idk. HP grass is used over grass knot b/c i hate grass knot, lol. and through personal use, it hits things like rotom-w a lot harder. the set is utterly walled by lati@s but that's not what it's made for.
some calcs on HP grass over grass knot:
88 SpA Life Orb Infernape Hidden Power Grass vs. 252 HP / 4 SpD Rotom-W: 120-143 (39.4 - 47%) -- guaranteed 3HKO
88 SpA Life Orb Infernape Grass Knot (20 BP) vs. 252 HP / 4 SpD Rotom-W: 42-49 (13.8 - 16.1%) -- possible 7HKO
grass knot is pretty bad imo, lol