Well there's a number of different things you can try. Remember, you're stereo image can only translate what is actually happening in the room, you panning is set by where people are standing in the room!
That being said, there's a number of ways to go about it:
Spaced Pairs
1. Use a space pair of omnis. Despite what you might think, this actually works fairly well for stereo imagine, although it will capture a lot of the room sound, especially from "behind" the microphones. Be careful have having a hole in the middle of your stereo image if the two microphones are too far apart.
2. Use a spaced pair of directional microphones. This will capture less of the room ambience. Try a distance of about 1m between the two mics. Again, be careful of a whole in the middle.
Varying the distance between either microphone, and angling the directional pair differently will change the stereo width.
Near-Coincident
1. ORTF array: 17cm apart and at angles of 55deg off the perpendicular (the left mic pointing left, the right pointing right..) using cardioid mics. I've found this give a very good, natural stereo image, very representative of what's in the room.
2. NOS array: 30cm, 45deg off the perpendicular (same directions as ORTF)using cardioid mics. This tends to give a slightly less stable center; this is really good for capturing a wide stereo image, but tends to work better when coupled with an other, narrower stereo pair.
3: Faulkner array: 20cm apart, pair of figure of 8 mics. Very nice stereo image, perhaps not the stablest center images but still pretty good, and captures a lot of the room ambience.
Another good technique to use is the mid/side (M/S) technique. Use An omni and a figure of eight pointing "away" from the band (find a pic online to better explain this). You'll need a bit of decoding for this to work:
bounce down the omni and f-0-8 down to a mono file (no panning). Then, make a second copy of the f-0-8 original file, and phase invert on of them, then pan one hard left and the other hard right (the out of phase one needs to be panned hard right if your negative lobe is point right i believe).
You've now got your center imagine (the mono file), and your stereo image (the two f-o-8). Balance the two of them so that your stereo image is how you want it.
A good way to test your stereo image is to set the mics up and have some walk from far left to far right, at the distance the majority of the players will be at, making some noise. Just have the person talk about something continuously..ask them to recite what they've done from the moment they woke up to them walking up and down infront of these mics!
Pay attention to center image stability and also to definitions in the extremes of the stereo image..
But most of all, just throw a few different arrays up and try'em out! see what grabs your fancy..
