You could setup a page that when linked to with the proper URL parameters it will set a coupon code and add items to the cart. It is a custom piece though that would require a bit of hand coding to get working correctly.
The first thing you would want to do is setup the coupon code portion for the discount you would like to apply to these users. Once you get that part worked out you will need to craft a new page that will look for the URL parameters that are passed in a link and use these parameters to set the session variable for the coupon code, then add the items to the cart.
This page will have a set session value server behavior on it to set the session variable for the coupon. Next you will have add to cart server behaviors on the page to get the items added to the cart.
Once the page is crafted you can construct the link. If your items are static then you will need to add in each column's parameter for the item to the link including the item id, size, quantity, etc. If you have your items coming from the db then you can just pass along the item id. To make the link trigger the server behaviors on the page you will need to update the triggers for the set session value and add to cart server behaviors. You will need to set them to work on a URL parameter that you pass in the link.