Custom Cell Implementation For RadioButton

Hello,

I have implemented successfully Custom Cell for Radio Button through below link.

http://msdn.microsoft.com/en-us/library/aa730882%28v=vs.80%29.aspx#winf_radiobu_topic4

I need some help for setting by default selected radio button.

For eg i have 3 radio button in each row...and i want 3'rd radio button should be selected by default.

Please help