I figured out something that works, but I don't really like it. Would like to know from others why and if there is a better solution.
If I leave the:
Enabled="False"
out of my ASP tag and put
var btnfinalize = document.getElementById("<%=btnFinalize.ClientID %>");
btnfinalize.disabled = true;
in the javascript of my page the ASP button is enabled during design, disabled when the page loads and properly fires the javascrip function I want when later enabled (really disabled=false ) and clicked