You need to use tuples to write to many2many records:

In your case if the authors don't exist, and you want to create them, you would use:

orm_paper.create({'title': title, 'author_ids': [(0, 0, {'first_name': first_name, 'last_name': last_name})]

if the author does exist you would use:

orm_paper.create({'title': title, 'author_ids': [(4, author_id)]}) 

The following can be found at /openerp/models.py, and describes how to use the appropriate "triplet" 

:class:`~openerp.fields.One2many` and
:class:`~openerp.fields.Many2many` use a special "commands" format to
manipulate the set of records stored in/associated with the field.
 
This format is a list of triplets executed sequentially, where each
          triplet is a command to execute on the set of records. Not all
          commands apply in all situations. Possible commands are:

          ``(0, _, values)``
              adds a new record created from the provided ``value`` dict.
          ``(1, id, values)``
              updates an existing record of id ``id`` with the values in
              ``values``. Can not be used in :meth:`~.create`.
          ``(2, id, _)``
              removes the record of id ``id`` from the set, then deletes it
              (from the database). Can not be used in :meth:`~.create`.
          ``(3, id, _)``
              removes the record of id ``id`` from the set, but does not
              delete it. Can not be used on
              :class:`~openerp.fields.One2many`. Can not be used in
              :meth:`~.create`.
          ``(4, id, _)``
              adds an existing record of id ``id`` to the set. Can not be
              used on :class:`~openerp.fields.One2many`.
          ``(5, _, _)``
              removes all records from the set, equivalent to using the
              command ``3`` on every record explicitly. Can not be used on
              :class:`~openerp.fields.One2many`. Can not be used in
              :meth:`~.create`.
          ``(6, _, ids)``
              replaces all existing records in the set by the ``ids`` list,
              equivalent to using the command ``5`` followed by a command
              ``4`` for each ``id`` in ``ids``. Can not be used on
              :class:`~openerp.fields.One2many`.