Some googling here and here shows the settings on VS 2008, although this will depend of course on your options in the Advanced options in the Add Service Reference wizard.
Edit : Agreed - Never be afraid to drop and recreate service references from scratch. When working with version control like TFS, "update" service references there is often quite a mess as it figures which wsdl, xsd and disco files etc have been changed, added or deleted etc (and get filenames like SomeXSD92.xsd). Generally it is quicker to just drop and recreate them.
Johan's post is makes a good point (and can be used as part of a standard design pattern called Service Agent which handles the implementation of the client proxy).
I'm not quite sure what you mean when you say two tiers would need to reference the same assembly? If you are sharing type of the entities called in the service you would need to reference the entity assembly in most tiers anyway. For your Service Agent assembly project (which has all the service references) you can either re-expose the same Service Contract used by the WCF server or wrap it in a new interface.