SharePoint 2007: Moving main site, to be a subsite – How to urls be redirected/changed

The setup:

• SharePoint 2007 (MOSS Enterprise) on WINSVR03/IIS6
• One site collection, with one access mapping (http://mainsite) currently

I'm moving the main SharePoint site, in our one site collection, to be a subsite in a new site collection. I'm using SharePoint Content Deployment Wizard to complete this task (http://spdeploymentwizard.codeplex.com/).

The Question

So the main site http://mainsite being moved has many subsites, etc. I want to be sure that urls like this:

http://mainsite/subsite/doclib/doc1.docx

map to and redirect to the new url:

http://newsite/mainsite/subsite/doclib/doc1.docx ?

And furthermore:

I'm aware of this – http://rdacollaboration.codeplex.com/releases/view/28073 , however is it IIS7 only? That'd wouldn't work for me.

Looking at this question – Dealing with moved documents and sites in Sharepoint is the only one I see that is similar.

Would an IIS redirect of http://mainsite to http://newsite/mainsite work only for the root url?