Now that the new naming scheme for localization files in LR has broken Keyboard Tamer, you can use the following trick in order to continue using KT (example for the french language) :
1. In C:\Program Files\Adobe\Adobe Lightroom\Resources\fr, make a copy of TranslatedStrings_Lr_fr_FR.txt and rename it to TranslatedStrings.txt. Both files can co-exist since LR now totally ignores TranslatedStrings.txt.
2. In LR, launch Keyboard Tamer and make all the changes you want. Apply them and exit LR.
3. Replace the contents of TranslatedStrings_Lr_fr_FR.txt with the contents of TranslatedStrings.txt.
4. Re-launch LR and that's it.
For the English language, the procedure is slightly different since TranslatedStrings_Lr_en_US.txt doesn't exist by default :
1. Launch Keyboard Tamer in LR, make your changes and Apply. This will create a TranslatedStrings.txt file in C:\Program Files\Adobe\Adobe Lightroom\Resources\en.
2. Exit LR.
3. In C:\Program Files\Adobe\Adobe Lightroom\Resources\en make a copy of TranslatedStrings.txt and rename it to TranslatedStrings_Lr_en_US.txt.
4. Re-launch LR.
This will not work on the Mac since LR no longer reads the localization file on this platform for the English language (did you say "regression testing" ?).