Create and Add Custom/Configurable Option to Product Listing on Magento Website

The products would have option to be sold by weight (gms, kgs), litres (ml, litre) or quantity. Right now, I have added a simple product with custom option on my website as an example. The custom option appear on the product page & works perfectly. However, I want it to appear in product listing so that it can be added to cart from the listing itself. Currently a customised theme is being used which uses ajax to add to cart. The following work is required: - Create Configurable Attributes for Weight, Litre & Quantity so they can work different type of products for order - Add Custom/configurable option to appear on the product listing - Product be able to add to cart with custom/configurable from the product listing I would like to get bids from an experienced magento developer who can provide quick & high quality glitch free solution.