How to make .ASPXANONYMOUS cookie to be non-persistent cookie.

Hi, I do not want to set cookieTimeout property in anonymousIdentification element. If I removed the cookietimeout property it will dafault to 10000 min.So I was wondering if anybody know how to not set the time for .ASPXANONYMOUS cookie and make it a non-persistence cookie? Thanks
Currently its set as below in web.config file.
<anonymousIdentification enabled="true" cookieless="AutoDetect" cookieRequireSSL="true"/>