add/rem ****t rules progrmatically

I have a C++ COM app that is trying to manage NLB using WMI.
I am using "MicrosoftNLB_"   cl***** for this.
I could bind the NLB to NIC and also could modify the cluster setting.

Now i am trying to add/rem ****t rules to an NLB cluster.
None of the "MicrosoftNLB_" cl***** have methods to add/rem ****t rules.
I tried creating a new instance of "MicrosoftNLB_****tRuleEX" using
"IWBemWebServices::PutInstance".

Any pointers ?

Thanks -John