Boss wants the hotspot to limit each person that signs on to only 2 hours.
I know how to do that initially but since we use the same username and password for everyone logging in
my past experience is that the two hour limit starts on the first person to log in and then when that persons two hours
is up it kicks everyone off. How do/can I have each user have their own two hour limit with the same login?

Stop using the same username and password for everyone and use the trial feature instead granting each trial user 2 hours per day.

How do I change this to a trial log in from remote site?

<form method="post" action="http://10.5.48.1/login" name="login">

<input type="hidden" value="admin" name="password" /><br />
<input type="hidden" value="admin" name="username" />
<input type="hidden" value="http://www.ptera.net/newportal.shtml/" name="dst" /> <input type="submit" value="I Agree!" name="login" />
</form>

You don't log in for trials, you just get to use a specific amount of time without logging in and after that are shown a login screen.

If you need to show an initial disclaimer set a trial profile (also in the Hotspot server instance, where you enable the trial 'login' method) and on that user profile set an advertise URL pointing to the disclaimer.