update Script section of html from tidylib.

I need to update script section of the html through the tidylib
for eg.

<SCRIPT language=JavaScript1.2>
function funct1()
{
}
</SCRIPT>

should be updated to

<SCRIPT language=JavaScript1.2>
function funct1()
{
}
function new_function()
{
}
</SCRIPT>

ie I need to add one more function programmatically to script section of 
html document .

can i use function tidyNodeIsSCRIPT( <structTidyNode.htm>TidyNode tnod ); 
and proceed
please help me



Renjith.