Pseudo-Algorithm for MoveToCart
Set the CurrentQuoteId profile attribute to the quote record ID. As the MoveToCart method is row-sensitive, the current record in the Quote business component is the record to move to the Shopping Cart.
If the PriceListId profile attribute is not empty and if the Price List Id field in this quote record <> PriceListId profile attribute, then change the Price List Id for this quote. This triggers a reprice. Note that you need to use DefaultPriceListId instead of PriceListId if the user is not associated with an account that has a default price list.
If Quote Type is not Persistent Cart or Auction Quote, change it to Persistent Cart.