Well after thinking about this some more, I’ve realised that it was a bit of a dumb question to ask… My problem is actually being able to pre-define categories in themes for new subsites of my mulitiste.
I’ve got around this by using a premium plugin which allows me to offer blog templates / themes with a few predefined categories and some dummy content. This means that I already know the category id’s when a new subsite is created.
Now new users can choose any of my themes, and most of them will have an e-shop option which will have the dropdown “product” category pre-installed etc.
Good grief, the lengths I’m going to to try and simplify the whole wp cms 🙂
If anyone’s interested I’ll post a link to the full project here sometime soon (I hope).