My goal is to get a list of eBay categories programmatically.
It appears that the GetCategories method is only available from the Trading API. If I understand correctly, there is user interaction required to log into the Trading API: http://developer.ebay.com/DevZone/XML/docs/HowTo/Tokens/GettingTokens.html
Is there another method to get the eBay categories list programmatically?
I'm using Drupal 7, so PHP.
You do not need a token to get the categories. All you need is your App-ID
The link below with your APP-ID will return the XML category listing from site: UK (siteid=3) Setting CategoryID=-1 starts the list at the root level, you can start from any category, just use IncludeSelector=ChildCategories to get children
Now just use SimpleXML or whatever to parse.