Another possibility is to try Cunifer (sp?) brake lines. These are a DOT approved copper/nickle alloy line that is rather flexible to work with. With this stuff, you may be able find a way to snake them thru the tight spots. Here's a website for a shop that sells Cunifer lines, brake line hardware in general. Disclaimer that I've never used Cunifer yet or purchased from them, but the site is a pretty good reference:
http://www.fedhillusa.com/
PS - If you do end up using the Cunifer lines, please let us know how it went.