Update the preparation delivery time via the API

Summary: prestatic is looking for help to modify shipping and handling times with eBay’s API. He mentions that he managed to update inventory but not shipping times, despite his efforts with the documentation. He also asks how to get an unlimited eBay token, since the ones he generates expire quickly. jacquelinedu36 offers a link to instructions on shipping options, but that does not fully answer prestatic’s original request.

Hello, if someone can help me, I’m able to update the inventory with the API, but what I also want is to change the delivery or preparation time; no matter how much I read the documentation, it doesn’t work, so if someone can give me a lead or the solution.
Here is the code I’m using.

<?php

$post = '<<< EOD

<?xml version="1.0" encoding="utf-8"?>

<eBayAuthToken>v^1.1#i^1#p^3#r^0#.... Token </eBayAuthToken>

</RequesterCredentials>

</InventoryStatus>

</ReviseInventoryStatusRequest>

</ShippingServiceDetails>

EOD;';

Another question: when I’m on the developer section of the eBay site and when I generate a token it only lasts a few hours, how can I get a token that never expires?

thanks in advance