I often get to the point in building a new Magento site where 301 rewrites need creating for all the items on the old site. Is there a way of importing them directly?
Programmatically via a urlCreate() type Magento function would be fine as then I could just cycle through a csv.
Generally it's a good idea to stick with Magento's ORM for interacting with entity data, as there may be both business logic and storage logic which is baked into the entity ORM stack (this is notoriously true for EAV entities). But, depending on the number of records to be entered, a direct-to-db approach should be fine, especially if it's a one-off import. This is because URL rewrites are flat entities stored in the core_url_rewrite table (link), and the table itself has the necessary storage logic as part of its structure (mainly, unique request_path + store_id and an FK for core_store table). In other words, manipulating this data outside of the ORM tier is okay because the logic is part of the table definition itself.
Beyond this information, it's possible to load up a core/url_rewrite collection, create core/url_rewrite instances from the CSV and add them, and then call save() on the collection, but note that each item is saved individually. It might do to refer to the convert adapters for catalog entities and for customers, which is how dataflow works.