Hmmm, the set_text function is implemented in 1.0 which is not yet
released. So you'd have to modify the DOM yourself:
NODE.children("a:eq(0)").contents().filter(function() { return
this.nodeType == 3; })[0].nodeValue = "<b>Custom text: " +
TREE_OBJ.get_text(NODE) + "</b>";
Hope this helps till the next version is ready.
Cheers,
Ivan