impersonation ans microsoft reporting services

Hi all,
i've been reading a lot about impersonation and microsoft reporting services integration. there's a thread about it but here is the question:

I want to call report server passing in the url (something like   --  http://host/ReportServer?/ReportProject/Report&rs:Command=Render&rs:Format=HTML4.0/PDF/EXCEL   etc...   ).

As far as I can tell reporting services by default allow only windows authentication, so:
1 - my site runs under forms authentication, and i'll have a link to authenticated users (forms authentication) with permissions to see the report.
Now, I only want to impersonate the windows acount when i call this link and only then, because if i give acess to anonymous users (guest account or something) there's no point about the link anyway or seting permmissions (anyone who knows the url can see the report  :(    ).

I guess i'll have to set the link to an action and perform the impersonation on that action, but the examples i saw here create a webrequest witch means i'll have to handle the response. I only want to link to the url (with the impersonated windows account), is there any other way to do this?
I mean, if i handle the response how do I pass the result to the outsystems stream (I want to write the response on the page).

thanks.