The answer is : YES it can be done, the question is can YOU do it.
Unless you have indepth knowledge of php code programming, this will not happen.
The Tuney Auto User Configuration(TUAC) can be re-written and integrated into joomla (if you can access Joomla source).
Writing the RC and TAUC tables into the joomla database is the easy part, the hard part, you will have to incorporate the modified code from TUAC into the Joomla source at the right places to create the fields in the db, and set up the account on cpanel.
I would recommend changing hosts though, it would be simpler.
I sell RC hosting w/ 4 MySQL, 100 emails, fantastico, rvBackup, 70Mb +++ @ $4.95us w/ paypal
Alex