Using other config properties

your-storybook-preset.js

export const webpack = async (base, config) => {
  const { default: webpackMerge } = await import('webpack-merge');
  const { default: globToRegex } = await import('glob-to-regexp');

  // here we request the resulting entries property
  // and transform the array of globs to an array of regular expressions
  const entries = (await config.entries).map(globToRegex);

  return webpackMerge(base, {
    module: {
      rules: [{
        test: entries,
        loader: 'some-custom-loader',
      }],
  });
};