[Zope] Adding content to document types

Hello all, I'm adding documents & scripts to a folder using - context.manage_addDTMLMethod("index_html", "Index") #document name & title etc. These documents are created with default body content. My question is - how do I access/add to/replace the content that is inserted into the documents by default? For example, I'd like to insert dynamically generated code into Python scripts, or into the DTML document using properties defined within the folder. TIA. Samir.