>>> I was wondering what kind of approach anyone of you who faced this situation before have taken.
>
>Evolutionary prototyping, with very frequent deliveries in the early going. No other sensible choice, basically. See Steve McConnell's RAD book (MS Press) for other great hints for this type of situation.
>
>Oh, and work from a retainer <s> because, in all probability, most likely due to spectacular failure or great misunderstanding, your last bill won't be paid.

Thanks.