Hi,
sorry cant help you with the location of the switch... however i have just been looking on ebay and found this Audi all model manual on CD......
eBay.co.uk: AUDI Service Repair Workshop Manual all model 3 DVD CD (item 130030850529 end time 27-Sep-06 20:07:02 BST)
Im thinking of getting one just in case...
Cheers.
Rickt