To create /manage user or host accounts you need to create/manage LDAP and Kerberos 5 entries. Therefore, you could use ldapadd/ldapmodify (OpenLDAP) and the kadmin (Kerberos 5 MIT) to remotely manage Zeroshell.
The next week I am going to make a Bash script to remotely create/modify user account.
By using such script, you could create a web interface with PHP or CGI technique to administer Zeroshell without the problem of the limit on the number of admin sessions.
Regards
Fulvio