iRule check for user-agent and set cookie

Try this:

when HTTP_REQUEST {
    switch -glob [HTTP::header value "User-Agent"] {
        "*MSIE 6*" -
        "*MSIE 7*" -
        "*MSIE 8*" {
            if { not ( [HTTP::cookie exists "test"] ) } {
                HTTP::redirect "http://test-lab.foo.com:9610/CG510_APR_RedirectCapriURL/"
            } else {
                 what do you do if the cookie exists?
            }
        default {
            pool site-10.130.14.98_29710
        }
    }
}