ASP.Net 2.0 Authentication With SiteMinder

[GCeaser]

OK - So I know SiteMinder can work with IIS and ASP.Net 2.0. Here is
the problem, SiteMinder from what I understand requires a client on
every IIS box hosting a protected site that requires authentication.
The client catches incoming requests to URLs protected by SiteMinder
and requires the user to authenticate. The license for the SiteMinder
client is NOT cheap.

The problem: In a load balanced IIS web server cluster, I don't want
to have to incur the cost of having the SiteMinder client on every
clustered server. My thought was to configure all the ASP.Net 2.0
application to require authentication and point ASP.Net to a URL on
two separate clustered servers hosting a web service. What I would
then do is install the SiteMinder client on the two separate clustered
servers hosting the web service, and protect the URL for the web
service. Thus any time an ASP.Net application would try to access the
URL for the web service, SiteMinder would be invoked and
authentication would occur etc.

So the question is, has anyone done something similar to this and can
point in the correct direction? Any help would be appreciated.