If your data is in another MySQL table you can write a simple "SELECT" statement in MySQL Workbench like so:
a.`name` as `name`,
a.`password` as `pass`,
a.`email` as `mail`,
1 as `status`,
The first value in the select is the field in your old table, and the value after the word "as" is the corresponding field in the drupal users table.
For default values, just select a literal value:
'firstname.lastname@example.org' as mail
You then export that resultset as "SQL Insert statements" and then dump them into your users table.
I've never done this with Drupal tables before and I don't know the implications (effects on other tables), but I've done this previously to import masses of data from an ASP website into Wordpress posts table and it seems to work well.
Hope this helps, good luck