I'm not familiar with the gt6, but I can give you a general place to start. There's a few different guitar tones used in the ABITW series, and a good place to start is to turn off all your effects. You want to get a clean tone that's as warm as possible. Bass and middle @ about 1/2, treble and presence @ about 75%. If you don't have a presence control, raise the treble a notch or two and bring the mids up a hair. Once you have a warm round clean tone, add a bit of chorus. Set the depth rather high, about 75%. Set the rate low, and if you can vary the amount of wet (effected) signal, set it very low as well, 25% or less. Set the reverb for a small room tone.
That should give you a pretty good foundation to build your "wall" on (pun intended).
For the delay tone in the intro, take the same setting you just built, and do the following:
Delay - your delay should be set to about 420 ms and feedback at 4 (or 40%, depending on how your delay works)
Reverb - you want a larger room sound, more reverb "wash". If you're using a spring reverb, set the level higher.
Phaser - not really necessary, but if you want, you can apply a TINY bit of phase.
Bring your Mids up a bit, maybe 5%, and use your neck pickup
For the "Lead" tone, take your foundation tone and do the following:
Reverb - you want a bigger room again, this time think stadium or arena size.
Distortion/fuzz - this one's up for debate. David Gilmour
uses more different distortion pedals than you have strings. the main ones are the Proco Rat, Arbiter FuzzFace, and TS-9 Tubescreamer. That said, you can use a Distortion, Overdrive, or Fuzz to get a comparable tone.
Rotary - if you have one, use it. Slow rotation, and start at half depth and bring it up to taste.
Again, these tones aren't spot on, but they will get you close. Experiment with pickup selection and tone levels, and remember; A lot of Gilmour's tone is derived from very large interval bends, sometimes as much as 2 whole steps. Vibrato is also important. David has a very wide, slow vibrato that was produced with a "whammy bar" as well as finger vibe.
Hope that helps, if you have questions, let me know.
- Ryan -