browser based selection

yep, you could add an iRule event to the policy and then have branches for each browser. In the iRule, you'd just set the appropriate user agents to be matched so your iRule event expressions can pick them up.

You don't even really need to use an iRule. With an empty event agent and a few branch expressions, you can direct evaluation down different paths. Example:

expr { [mcget {session.user.agent}] contains "MSIE" }
expr { [mcget {session.user.agent}] contains "Firefox" }
expr { [mcget {session.user.agent}] contains "Chrome" }

As Jason said.

Alternatively you could use a general purpose action, similar to this:

Solution 12235