I currently have a button which sets the default value of a lookup field using

{!URLFOR($Action.Website_Inquiry__c.New, null, ["CF00N80000003bF14"=Patient__c.Name,"CF00N80000003bF14_lkid"=Patient__c.Id])}

The issue is when deploying as a package the custom field Id's in the other target instance (the one the package was installed on) are not the same (naturally). I saw a post here http://community.salesforce.com/sforce/board/message?board.id=ajax_toolkit&message.id=6810 which suggested that ID's will be replaced automatically with the new ID's. But i tested this (with unmanaged and managed Beta packages) and they did not get replaced. 

How do you set default values for fields on buttons that will be packaged? Thanks!