[support] Programmatically adding cck field to module defined content type

[Christopher M. Jones]

I did search for this, but I'm still finding my way around the various 
resources and the answer is not clear to me. Can anybody tell me, or 
point me to documentation that tells me, how to add a cck field into a 
content type I'm creating from my module?

I want to add a multi-value nodereference autoselelect field from my 
implementation of hook_form(). Or should I be doing it from 
hook_nodeapi()? Where / how do I do this in my .module file?