Attachments SharePoint 2007 List - Adding attachment using custom form to a document library

I have tried every possible scenario for adding attachments to a SharePoint list using a custom form with no success. My thought is to try to add the document(s) to a document library and build a field in the list with the link to the document(s). So here are the steps I want to accomplish and what has been accomplished already:

1. Custom list form (New Form) - accomplished


2. Attachment add in the form to add to a document library


3. Custom list form (Edit Form) - in work Currently causes error


4. Attachment add in the form to add to a document library


5. Custom display form displaying attachments from the document library using document ID(s) to show document link(s).

Does anyone know how to add documents to a document library from a custom list form?