HELP - Fast add-to-cart function

[montessori]

How can I modify OSC product listings (main page listing, not left column) so that from the same page, visitors can simultaneously

 

1. see list of products

2. be able to select attributres/options for one of the products

3. activate "add to cart"

 

For example

1. Page lists shirt, shorts, and pants

2. Customer select shirt, colour = white, size = medium)

3. Visitor adds to cart without going through the "buy now" process which requires 2-step purchase / selection of options/attributes