this script needs python2.6, does not work with 2.5.
Index: trunk/generate.py
===================================================================
--- trunk.orig/generate.py	2010-03-18 19:01:01.000000000 +0900
+++ trunk/generate.py	2010-03-19 17:09:06.000000000 +0900
@@ -14,8 +14,8 @@
                     kern_class += 1
                     font.addLookupSubtable(lookup, subtable+" pairs")
                     kclass   = font.getKerningClass(subtable)
-                    klasses1 = kclass[0]
-                    klasses2 = kclass[1]
+                    klasses1 = list(kclass[0])
+                    klasses2 = list(kclass[1])
                     offsets  = kclass[2]
 
                     for klass1 in klasses1:
