Nicholas,
I pulled this from the same documentation (section 1-6), which might help:
"Call the New User Signup command (SU) on the Partner page (p.php).
This command requires a WebEx identity (WID)—which is a user name—and a password, as well as your organization’s unique WebEx Partner account identifier (PID). After this command has created a new user account and established an authenticated connection between your Web server and your site on a WebEx server, a user can request services. For additional information, see:
“SU: New User Signup command” on page 2-28
“Signing up a New User” on page 3-2
“Creating a New User Signup Page” on page A-5"