cookie insertion

The wiki is your best friend...for this rule, we'll use subsets of the "HTTP::" command

http://devcentral.f5.com/wiki/default.aspx/iRules.HTTP

Here's a list of all the commands.

http://devcentral.f5.com/wiki/default.aspx/iRules.Commands

when HTTP_REQUEST {
    if { [string tolower [HTTP::uri]] contains "/folder" } {
       HTTP::cookie insert "name" value "value" } }

That rule will insert a cookie named "name" with a value of "value" whenever the URI requested contains "/folder" You might want to replace "contains" with "starts_with" depending on your requirements. You'll also want to add an expiration or path if you need it.

http://devcentral.f5.com/wiki/default.aspx/iRules/HTTP__cookie.html shows all the options.

Let me know if you have any other questions.