I recently did this with a '98 A6. Instrument cluster will not be a problem, as long as the speedometer has markings on it for kilometers/hour (while I'm sure it does). Odometer in miles is not a problem, and this may be resettable by a dealer or with a Vag-Com.
The one thing that you will need is the installation/activation of daytime running lights (DRLs) in most Provinces (Ontario and Quebec for sure), and verification that the car does not have to be modified to provide infant car seat anchor points. I believe that all Audis imported into the US since
1997 do comply here.
-- Jay. (remove dashes for legal email address)