Actually, you could do things this way:
Code:
LOCK TABLES inserttable WRITE;
INSERT INTO inserttable... <your insert statement>;
SELECT autoid FROM inserttable
WHERE autoid >= LAST_INSERT_ID();
UNLOCK TABLES;
That will give you all the ids that were inserted. I know that MyISAM tables do not use ids missing from the middle of the table, so you are safe there. The LOCK TABLES statement will guarantee that nobody interferes with your insert.