Data Controls :: Fire RadioButtonList / SelectedIndexChanged Event Conditionally For Some Items?

i read article "using javascript with asp.net radiobuttonlist control" and i found it useful.

[var RB1 = document.getElementById("<%=RadioButtonList1.ClientID%>");
var radio = RB1.getElementsByTagName("input");
if am setting radio[1].checked = 1; the item is checked. ]

step1: radio[0]=checked
           radio[1]=not checked
            radio[2]=not checked

step 2: by using javascript , am changing the selection

now 

           radio[0]=not checked
           radio[1]=checked 
          radio[2]=not checked

step 3: if am changing radio[0]=checked by clicking, it wont fire the selected index change that i wrote on code behind

but if am changing radio[2]=checked by clicking, it will fire the selected index change that i wrote on code behind

My requirement: i want to fire the selected index change in both cases. for that i need to change the selected index in step 2.