I'm refreshing my myself on installing an amp in my Elegance - it's been 17 years since I last did it (!) - and I came across this excelent reference site in America...
There are step by step guides here:
http://www.crutchfield.com/S-2dcbIQf...ps.html?page=2
And a basic video guide here:
http://www.crutchfield.com/learningc...tml?format=mov
Good reference, if like me, you want a refresher - or panicing over a simple job!