URGENT -- editing QXP default character style sheet specs?

Well, it’s not urgent but it would be very, very helpful …

I’m looking for an AS routine that will allow me to change the default character style sheet in a Quark 4.11 document from Helvetica to whatever font is the opposite of Helvetica.

I cannot for the life of me find a way to do it, and the Quark forum was not very helpful, seeing as how Quark killed it off long ago.