[imp] Need to use existing session vars in horde app

[imp at mynameisgabe.com]

Hello! 

I'm having an issue with accessing existing session variables with Horde.
This is a client's setup, so changing architecture at this point is limited,
including upgrading Horde/Imp. They've done some customizations, so I don't
want to risk wiping anything out or changing any functionality for existing
users.

Here's my setup:
  Imp 4.0-ALPHA (taken from help:about, don't know if this is accurate)
  Apache/2.0.46
  PHP 4.3.2
  mysql  Ver 11.18
  IMAP4rev1 2003.338rh

Hopefully that's enough info.  =)

My problem is this, I have an existing php app which sets a plethora of
session vars on login.  Then, once logged in, you can perform many non-horde
related tasks and you can access Horde as though it were just another part
of the same app. The way I would like it to work is to autologin using the
session variables set on the initial login.  However, when the user crosses
over into Horde, it seems as though it starts its own session and I cannot
access my variables. =(  Is there a way I can access data from the other
session while in Horde?  

I tried playing around with the Horde session name in
$conf['session']['name'] but if I change the name from "Horde" it won't
allow me to login.

Thanks!

Gabe