Require Content Taxonomy for populating form with terms?

No it is no requirements for populate core taxonomy, you can use vocabulary_id for assign terms to node. For example, if your vocabulary id is 3 then URL will be:
http://www.yoursite.com/node/1/edit?3=term1||term2||term3

lucky i found (and searched for) this. It is not mentioned on the main page, is it?

Fantastic.
Could we add this and the content taxonomy syntax (ref: http://drupal.org/node/622018) to the examples on the module project page? That would be a great addition to the documentation.

Example:
Case 4
You have a core taxonomy with multiple terms. You want to provide a link which will select 3 terms. Specify your vocabulary id and the term ids, using this format: http://site.com?vocabulary_id=tid1||tid2||tid3. For example, if your vocabulary id is 3 then URL will be:
http://site.com/node/1/edit?3=term1||term2||term3

Case 5
You have a content taxonomy field with multiple terms. You want to provide a link which will select 3 terms. Use this syntax:
http://site.com/path_to_page_with_form?field_cck_taxonomy=1||2||3
where field_cck_taxonomy is the field name and 1, 2, 3 - are term IDs.