Alright . . .
For starters, I would recommend going with a square, wooden beater. No felt beaters. During sound check, listen really carefully to make sure you're getting some good, solid beater slap. If you're not, then you might try the silver-dollar trick. Kinda' cheezy, but supposedly works.
Secondly, I would come up with a good strategy on how to deal with what will likely be a lot of loud cymbal -- pretty common with that genre of music.
If he likes to use 3 crash cymbals, try and talk him down to two. If he uses 4, try and talk him down to 3. That sort of thing. Secondly, impose your authority and force him to use smaller, darker ones.
Custom K darks are great, but there are a few others that work well (dark&crisp, etc.). Do whatever you have to do to get some for the day. Borrow or rent if you have to.
Make sure the bass player re-strings before the session. If he doesn't, then hit him in the face. Seriously. Do it as hard as you can.
On second though, bass players are usually pacifists, so it probably wouldn't be nice.
Lastly, find out what kind of amps the guitarist/s are going to be using. Make sure they are of high quality. For that genre of music, I tend to think Marshalls are good recording amps. I just always seem to have good luck with them -- even the solid state ones aren't bad for the really heavy, crunchy death-metalish stuff.
Obviously, if anyone has access to a dual rectifier or any kind of Mesa, that would be nice, but most of these bands don't have that kind of cash lying around.
Just make sure that it sounds nice over the monitors and records well when micing it up. Pay attention during sound check. And I mean
really listen and be honest with yourself; is it
really getting you a good, ballsy tone, or does it kind of get lost sometimes and sound thin and noisy, screechy, etc. ? If that's the case, then keep playing and fiddling with it. And back the distorion off a bit -- you don't need nearly as much when you record as you do live. If it's still just not doing it for you, then stop the damn session and tell them to get a real amp if they want to sound any good.
The biggest problems I have with these kinds of bands are: Loud, harsh cymbals that sound like shit . . . bass drum that's too flabby, not tight enough, and not enough click . . . old bass strings that need to be changed . . . and guitar amps that sound good when rehearsing but just don't record well.
