if this is an option for you, i suggest, that you upgrad to 3.10.
3.10 includes an AJAX-bases treemenu "out of the box". I don't know, if it is base on Kristian's solution or another, but it works very well.
See http://ez.no/doc/ez_publish/technical_manual/3_10/reference/configuration_files/contentstructuremenu_ini/treemenu/dynamic for details. You'll find information on upgrading here: http://ez.no/doc/ez_publish/upgrading/upgrading_to_3_10/from_3_9_x_to_3_10_0
If this is not an option: What do you mean by "old menu"? So, what did you use before / what do you change?
