FWIW:
On the 2006 SE, do you have a clock in the drivers display? If so then at a minimum you will loose that.
caverD3 has some info on the Aux Input:
"Yes you can wire into the aux in either behind the head unit or behind the cover in the passenger footwell.
See:
http://www.disco3.co.uk/forum/topic7072.html
http://www.disco3.co.uk/forum/topic24181.html
http://www.disco3.co.uk/forum/topic21220.html
http://www.disco3.co.uk/forum/topic20175.html
http://www.disco3.co.uk/forum/topic9018.html "
Cheers,
AP

