Multiple servers or CSPGateways

Hello to you all,

Strange  titel, so I'll explain better:

I now have IIS-server with a CSPGateway installed. This works fine. But I want to use a rest-service  (or another zen-page, whatever.) on another cache-server

So on IIS i have an application called CSP. (/csp) This contains the handler to map it to the CSPGateway. 
It has been configured to acces a cache-server (X) which will handle the request. But now I want, in this case, the request to be executed on another cache-server(Y).

I can add other servers in the CSP managementportal, (now it had only LOCAL and csp) but how will IIS know which server I want to use for the request?

Bert regards,

Simon