Rails 3.1 asset pipeline and manually ordered Javascript requires

I am trying to convert an existing app to the new 3.1 asset pipeline layout, and want to include a lot of vendor files that have to be in a specific order, (underscore.js and backbone being one pair). As such, I can't just use a = require_tree . to pull in my vendor files, (without renaming each file with a prefix. Yuck).

The following is within my app/assets/javascripts/application.js file:

//= require modernizr-1.7
//= require jquery-1.6.1
//= require underscore-1.1.5
//= require backbone-0.3.3
//= require_tree .

I have tried every combination of with/out extensions, with/out the require_tree and with/out the relative paths, and nothing works. All of my vendor files are in /vendor/assets/javascripts/.

I feel like I am being stupid because this seems like such an obvious use case, (including specific files by name in an order is common with JS, no?) that I must be doing something idiotic?