If anyone is using RaiderSoft's chat at the Platinum level, here is a custom authentication script for it.
If you go to your RaiderSoft control panel, click User Accounts, then Options, scroll to the bottom and select "Custom Authentication Script". In the field, enter:
http://www.yoursite.com/ubbthreads/chatAuthentication.php
or wherever you upload the file to.
Then if you pass the following params to your chat applet:
<param name="username" value="$Username">
<param name="password" value="$Password">
<param name="autologin" value="yes">
You will be automatically logged in when you invoke the applet. The authentication script also takes advantage of the return value of 2, which grants moderators and admins chat room op status (they can kick and ban and such).
Cheers,
Chris