ESS from home via Microsoft ISA server

We've been presenting ESS from home with Microsoft's ISA server for a few years.  It was on 8.0.  It was no problem at all routing a public, secured site through to the ess application I built outside of the portal (it's just frames presenting the links)

However, we've just upgraded to 9 and it's a problem.  The new ESS site I built is with iframes and works great in the network.  However, when trying to offer it up over the internet, the new Lawson security system throws a wrench in to it.

The problem is that I can see the SSO servlet ok but the pages that redirect to the login form cause the CLIENT to refer to the internal name, not the external name. (I hope that makes sense).

I need a solution and I was thinking of the grey and black box services.  i don't know anything about them yet but I figure if I can build a login form that uses (but doesn't redirect to) the SSO servlet I can get it to work.  Does anyone have any ideas?