You will have to modify the source of thise components. You will need Flex Builder 3 and the LiveCycle SDK. That is where all of the source for Guides is kept. Also there is a customizing form guides document that explains what you need to do.
Yes .... the mapping between the XDP and the guide objects does not change. When you are in guide builder you can take your field (XDP) and ask for an alternate display. This is where your custom component will appear. If you base you custom component off of one of our components then the mappings will be done for you. If you start from scratch, then no mapping between the two will exist.