Maybe the Grouped product type is for what you want.
You can create a Grouped product and then add child products to it. A grouped product (with the child products) can be added by one click.
See WooThemes docs.
Edit:
If it’s not what you’re looking for, try to search for submitting multiple forms with jQuery (maybe this one), and have a look at this question about AJAX add-to-cart:
Woocommerce – Add a product to cart programmatically via JS or PHP