Custom response Cookie in OAM 11G R1

We are integrating Telligent software to OAM, Telligent supports SSO using a cookie CSUser. The contents of the cookie should have key value pairs like below -

 Response.Cookies["CSUser"]["username"] =      "someCookieAuthUser";
     Response.Cookies["CSUser"]["emailAddress"] =  "someuser@blah.com";

 We can set a cookie as a response but the structure of the cookie which Tellligent is expecting seems not possible OOTB.

Can anyone please help? I am not sure if we can use a custom authentication plugin becasue our OAM talks to SITEMINDER for authentication. So we just need to set the response in OAM not authentication.