How can i add or set more email tokens in my drupal 6 site
i guess you want more tokens in the users settings page admin/user/settings (D6), according the format of your token (!username)

This page is a bit special because it is a core feature.
cf User settings

Token module provides more tokens like [my-token] but this cannot be applied in the admin/user/settings

If you want more tokens on the users settings, i suggest to use a custom rule (fire on user's creation) with the rules module