Hej Henrik,
Require normally works by having each library independently declare its own dependencies, as such, it becomes a little harder to declare dependencies after the libraries have been published.
You've a few options.
1. You can use Modernizr.load as is used in the core/src/scriptLoader.js
2. You can nest a require statement inside your define (require example)
3. You can try using require.config({ shim: { lib1: { deps: [ 'lib2' ] } } });
4. You can edit the library and add the correct dependency to its define statement
I hope that helps.
Ollie