I know this won't be what you wanna hear lol ,
but i spend fecken hours and hours positioning mics and fiddling with my 5150 to get a good distorted recorded sound and none of them ever sounded right to me and i wasted alot of time on it ,
I picked up a pod 2.0 put it on one setting and whilst it's not perfect sometimes it takes me about 2 seconds to do and set up and i'm more than happy with the sound .
having said that putting the mic up right up against the speaker in the lower left hand side of the cone is great .. some people put it in the middle but you'll find that bypasses most of the sound and tone that comes from the amp .
good luck !