What advice would you give to someone trying out for a lead guitar position in very demanding metal band such as Necrophagist, Human Abstract, Arch Enemy, The Faceless, or Dragonforce.

Haha PS I know these bands are all very different sub-genres of metal to ensure that there's no bias, so no commentary needed on my example choices.
not really that different...super fast shreddy sweeping solos :P
so..legato and shred..sweeping..you are there
just play some decent sweeps, like 5 string ones, some wicked legato with a few taps in there.. also demo your fast muting on open notes :P
have hella long hair like the guy in human abstract.....and own everyone in the band. and make them make you sandwiches all day..
Make sure you gel with the band....
Gibson LP w/SD59+PRS Dragon II
Fender 52RI Hotrod Tele
PRS Tremonti SE w/Bulldog Extremist/Black Label

Cornford MK50H & 2x12
Marshall JMP-1

TC Electronics G-System

MacBook + Ableton Live
Quote by JOn`
Make sure you gel with the band....

Cool, I'm liking these responses.

How does one gel with a band?
To gel you need to become a band member. You need to be able to integrate into what the rest of the band is doing etc. Not just be there playing guitar while the rest of the band do their thing
Learn to play realllllllly well.

Play with attitude.

You need to be a technical beast. You need to be able to write original material. You need to be able to shut up and listen to your bandmates. You need to be able to get along with people.
Well for leads often times making a an arpegio based around a chords but now sweep picking it sounds pretty dope. Try resolving on the arpegio. For eminor play an arpegio that resolves on E, then G then, B, the D# or something. Try tremolo picking scales really fast but not scale burning, choose where you start and where you end and how your hammer ons and pulls lead to the next note notes. Try string skipping octaves, do your bends really slows and deliberate the necrophagist. Try different chords inversions and changing tonal centers. Also use pedal tones. Sweep picking a 3 strings shape and moving up and down a scale with your tapping finger and or pinky. Weird patterns that sounds like they dont make sense until you play them over and over. Dimished patterns are key, know how they fit in harmonic minor and phrygian. Try to move all over the fretboard, this can be acheived with sweep picking. Connect different sweeps with a tapping finger. Know what chords your playing over (duh). Keep a tempo, use triplets patterns to get up and down the fretboard, but dont overuse because then you'll be boring. Bends stuff weird, play the wrongs notes, mix up scales but know which ones you are mixing up.

I hope that made sense.