Well pretty simple, following your example:
protected void Page_Load(object sender, EventArgs e)
{
int x = 1000;
BtnPrint.Attributes.Add("onclick", "javascript:"
+ BtnPrint.ClientID + ".disabled=true;"
+ Page.ClientScript.GetPostBackEventReference(BtnPrint, null));
string Script = @"<script language ="'javascript'">
window.setTimeout('enable()', " + x.ToString() + ")
function enable()
{
document.getElementById('$BTNAME').disabled = 0;
}
</script>";
Script = Script.Replace("$BTNAME", BtnPrint.ClientID);
Page.ClientScript.RegisterStartupScript(GetType(), "script", Script);
}
Cheers