I don't see why you want to use the redirect in Contribute.
You just have to make connections to the different folders in
Contribute (in your case it seems to be three connections:
http://www.documentaryaustralia.com.au/da/index.php,
http://documentaryaustralia.imagine-hosting.com/da/index.php,
http://www.inthecompanyofactors.com.au/itcoa/index.php)
and then you administer these three connections throught Contribute
admin section, adjusting Users and Roles, making Connection keys,
etc.
What you have as a result a three 'sites' in Contribute with
there own connection and administration, but within the same
domain.
When you do not want that, you just provide your users with
bookmarks (main menu) to the three main folders/pages, so they can
start browsing and editing from these starting pages.
I don't see why you want to use the redirect in Contribute. You just have to make connections to the different folders in Contribute (in your case it seems to be three connections: http://www.documentaryaustralia.com.au/da/index.php, http://documentaryaustralia.imagine-hosting.com/da/index.php, http://www.inthecompanyofactors.com.au/itcoa/index.php) and then you administer these three connections throught Contribute admin section, adjusting Users and Roles, making Connection keys, etc.