Tk and Tkx are both built on Tcl but the interfaces are different. Tkx uses a mildly more perlish interface.
I've never translated Tk to Tkx but my first suggestion would be to go to the top of the script and change 'use Tk;' to 'use Tkx;' when you have Tkx installed and run the script to see what breaks. You can look up the section that is broken and convert to the new code here I think some of the old Tk style still works because not all Tcl elements are built as widgets and you still have to call them in the Tk way. I'm just not sure if having a widget in Tkx excludes the old Tk syntax.