Good advice...
Just practice to their recordings, act confident and jump right into your audition to see if you guys all sound good together (and sometimes more importantly) can stand hanging out together for long hours or not.
I'd suggest playing simple and tasteful bass lines that are played very well instead of trying to show off many of your fast runs or flash unless that style is truly appropriate for their tunes.
Start out with the mindset of just supporting the songs and really listening to what the drummer, rhythm-instruments and the vocals are doing. (what you play must somehow complement what they've already got going)
Most of the bands I've played in have had one person that definitely has the best timing, (it isn't always the drummer or myself) so pay particular attention to this persons playing and what he does...
If you don't get this gig, you may find that you like the 3rd or even the 10th band you try out with much better, so just keep at it till you find the right fit.
If your not doing it already, try practicing along to recordings of other bands to help get your mind out of being a bedroom-bassist and more into band mode.
Good luck...
