Disable Option List from Javascript

Can someone provide some code demonstrating how to disable an ASP.Net option list control from the client-side using javascript? I can disable textbox and select controls by using the following:

document.myForm.myTextBoxCtrl.disabled = true
document.myForm.mySelectCtrl.disabled = true

But this does not work for the option list control. Please help.

Thanks :)

By Option List, do you mean RadionButtonList ?

Yes. I apologize for the mistake :) I am referring to a RadioButtonList.