add/remove multiple downloadable products to cart in one shot

Hello All,

Advance apologies if this newbie question has been previously answered. I would appreciate a pointer (as I couldn't find anything appropriate).

I'm setting up a store that only sells downloadable products. Thanks to the tutorials here (especially Ajeh's posts), that was a breeze.

Now, I'm trying to configure the cart so that a customer can select (check) some number of the products listed and, with a single click, add them all to the cart. In the default 1.3.7 setup, is it possible to do this for downloadable products? What configuration incantations do I have to invoke for this?

Of course, once this works, then the next step is to have it so that the same checkbox (or something similar) will remove a previously added product from the shopping cart.

Thanks much,

DM