TemplateReplaceAll implementation?

Hello, I'm trying to use the templates to insert code into existing code rather than replace everything. The docs say this is possible via the TemplateReplaceAll = false config code. I can't seem to get this working at all, no matter what I do, the templates dialog always says that it will replace everything, and sure enough it does.

I looked in the code and saw that in fck_template.html the message "the actual contents will be lost" is hard coded with no apparent knowledge that maybe sometimes, this won't be the case. Also, and maybe this is nothing, but the template insertion code calls a function called SetHTML and at least in the API, SetHTML always replaces the code in the editor, whereas the InsertHTML method is the one that inserts into existing code.

So has anyone got this working that would care to share the technique with me?

thanks

John