[gkarlsson]

Your best bet would be to look at one of the pre-defined shipping modules like FedEx.
You will find this in /classes/XLite/Module/CDev/FedEx.

You will be able to see that the majority of functions relate to getting data and processing it - you could strip these out and remain with the core functions necessary to perform your tasks.

The core functions can be found in the subfolder Model\Shipping\Processor\fedex.php. This should give you a good point to start producing what you are looking for.

When in doubt, or when there is insufficient information or documentation, always have a look at how other modules do stuff.