Building a localised SeaMonkey 2.42

Hello,
I have successfully compiled SeaMonkey 2.42 from Dave Yeo's sources. Now I  
want to build a localised (German) version.
My plan is to
1. Download this  
https://hg.mozilla.org/releases/l10n/mozilla-release/de/rev/SEAMONKEY_2_46_RELEASE  
German locale tarball and the corresponding en-US one,
2. unpack the German tarball to D:\gecko45\locale_de and the en-US one  
anywhere else,
3. compare the files from the en-US 2.46 language pack with the ones from  
2.42 and edit the German ones so they are at the state of 2.42,
4. add mk_add_options MOZ_CO_LOCALES=de, ac_add_options  
--enable-ui-locale=de and
ac_add_options --with-l10n-base=/gecko45/locale_de to my mozconfig file,
5. build.

Can someone tell my if this will likely work? Are there any missing steps?  
Or is there an easier way to do this?

Many thanks,
Laurenz Sommer