I just watched on YouTube a video by GPVlog, detailing how to dismantle a centre console for 04+ (his car is an 08 GXP); apparently you can replace the pigtail under the console with one that supports HUD, and it plugs in right at the front of the console, just in front of the shifter. For those of us who have plug & play with the heads-up projector but can't find a convenient controller lead, I think that's the answer right there! Obviously I'll explore this a little more before saying for dead certain, but it's a big start!
