You probably can use the GUI builder you found if you take the TCL code it produces, and translate it to Perl by hand. It should not be too hard if you can find the equivalents.

(please note I have never written a single Tk GUI in my life, so I don't know how hard this might be)

Otherwise, you could try a different toolkit. Check whether the perl bindings for Gtk2 or Qt are easy to install (for Windows), and find a GUI builder for them. I can at least vouch that Gtk2's bindings look very similar to the C code the GUI builders often generate.