it's simple really, i had 1 radial gradient black to white starting where the "highlight" is plus 2 linear gradients black to zero around the lower corners or smth (I don't really remember exactly). all the gradients are separate layers in either "soft light" or "overlay" mode. done! you just have to play with it a bit to ged a hang of things and get the radiuses and amounts you like.
When I saw you posted this comment on mangion's rip of this texture, I figured I'd link you to this one (the original) but seems you've already found it, since you copied and pasted mangion's name and all even though this isn't him