Has anyone gotten weight based shipping to work?

It looks like you need to use an array to pass the weight and price values, however there is no example code that demonstrates how it should be done?

/**
* Calculates the shipping cost of an order, by taking the products
* and calculating the shipping weight, based on an array set in _config
* ASSUMPTION: The total order weight can be at maximum the last item
* in the $shippingCosts array.
*/

Any clues / ideas?

Thanks in advance