I have tried, in vain, to invoke hook_civicrm_tokens and hook_civicrm_tokenValues in a Joomla instance in order to add custom tokens (to be specific: relationship information).
I created a Joomla plugin to allow this, as this seems to be the recommended way to implement hooks in Joomla, to no avail. I have been unable to discover how the mail form gets its list of tokens in case I need to prefix the call names with that module, e.g. Mailing_civicrm_tokens. I've looked at: