Hi!
This whole post is just MY OPINION. Your mileage may vary!
First of all, check out the guitar tone here:
http://www.mp3.com/Badwolf
on songs like "Richard" and "Armed And Dangerous".
now go here:
http://www.mp3.com/HotterThanKarl
and listen to "Self-Destruct For Me"
I can tell you how I got those tones, because I was recording engineer (and guitarist) on those recordings.
First of all, the SM57 is my preferred mic for guitars, so you're fine there. Here are my tips
1) Use a decent guitar. For a "Scorps" sound, you'll need something with quality humbuckers (like the better Gibson stuff). Make sure intonation and fret dress, etc are up to snuff. I'd stay away from high-gain pickups like the EMG's if possible, but you can work around them if necessary.
2) Use a decent amp. Ideally, you'd start with something all-tube (ideally a Marshall 2203, 2204, 1959, 1987; but you can make it work with a Fender Super Reverb, Deluxe Reverb or Champ,
Vox AC-15 or AC-30, or any similar well-constructed all-tube amp). For higher-gain 80's stuff you'll probably need to add a GOOD overdrive pedal like
the Ibanez TS9 tube screamer.
Starting with a warm, ballsey amp is 99.9% of the battle. Start with a high-gain, solid-state buzz machine and the battle is already lost. Even a $125
Fender Champ from the 70's will sound incredible with a Tube Screamer pushing it, and running into a 4x12 cabinet. Which brings me to...
3) Use a decent, closed-back cabinet, preferrably a 4x12 by Marshall or one of the better Ampegs, but even a 1x12 or 2x12 can work well if it's a decent cabinet. Find something with some warm speakers. I like
the Celestion Vintage 30's, but I also have an Acoustic 4x12 with old Eminance speakers that sounds incredible, so you don't have to spend a ton of money. Just use your ears.
4) Another REALLY important point. Get some good, sealing headphones, crank up your amp, put the mix into your headphones and start moving the mic around. You can change the tone DRAMATICALLY with mic placement. I usually start with the mic right up to the grill of the cabinet and about halfway between the center and edge of the speaker. But move it around. Moving the mic toward the center of the speaker will usually give you a brighter sound. Toward the edge, a darker, deeper sound. Moving the mic farther away can give you some intersting colorations, as can moving it off axis.
Bottom line... use your ears and let them be your guide. You've probably got time, so put it to use and experiment.
Good luck, and feel free to email me with any questions!