Do I need to configure anything to use scripts/custom CSS on a project home page?

Yes, you will need to enable the "Preserve HTML head content" check box in the 'Edit project' page if you're referencing CSS and JavaScript from within the <HEAD> of your document (Note: This option first need to be enabled for the domain (under Administration -> Configure -> Project defaults)). This is not recommended if you use office productivity or "WYSIWYG" Web editors to edit this content. You can use inline CSS within the page <BODY> to override selected styles. Some JavaScript embedded in the body of a document will work as well (e.g. referencing an external RSS aggregator, etc.) See the links below for the help files on this (replace open.collab.net for your own domain to view the docs on your own site).

Related information
http://www.open.collab.net/scdocs/RemoteBranding.html.en
http://www.open.collab.net/scdocs/ProjectOwnerCustomStyle.html.en