My dealer did it for someone and quoted 5 hours labour. It then took them way longer. It seems they would have to be mounted to the chassis and I could foresee having to remove all the lower side trims. Let me know if you achieve it because the OEM parts are not that expensive (£300). I wouldn't go for the generic parts if I were you.

2007 Q7 SE 3.0 TDI (Air, Xenons, Tech Pack, Dension Gateway 500, Off Road front and rear)
2006 A6 Avant 3.0 TDi Tip S- Line SOLD
2003 A6 Avant 1.9 TDi SOLD
2002 Allroad 2.5 tdi Tiptronic SOLD
1997 A8 4.2 Quattro SOLD
1999 S4 SOLD
1997 A4 1.8T Sport SOLD