The spoiler tag was only included as an example of how to add additional tags via the extratags function.
To get the functionality you are looking for would just involve modifying that example code.
here is what it looks like now:fString = doCode(fString, "[spoiler]", "[/spoiler]", "<font color=""" & CColor & """>", "</font id=""" & CColor & """>")
you could change it to this:fString = doCode(fString, "[spoiler]", "[/spoiler]", "<font size=""1""><strong>Spoiler Alert!</strong> (highlight to read)</font><hr size=""1""><font color=""" & CColor & """>", "</font id=""" & CColor & """><hr size=""1"">")