Broccoli-rollup is a simple wrapper around Rollup. In the options object pass the rollup options.
var rollup = require('broccoli-rollup');
var lib = 'lib';
module.exports = rollup(lib, {
inputFiles: ['**/*.js'],
rollup: {
entry: 'lib/index.js',
dest: 'my-lib.js'
}
})