http://graviteam.com/forum/index.php?topic=11209.0 This guy got it working...
Just for the record in case somebody needs it. I eventually figured out how to convert the German edition to English: there are probably easier ways of doing it, but I could not find them and this is the way I did it.
1) install german edition (v. 1.0)
2) goto ...\Steel Armor\data\mtc80\
3) rename the folders "loc_ger" and "loc_ger - 1.0" to "loc_eng" and "loc_eng - 1.0"
4) goto ...\Steel Armor\data\mtc80\dev_updates\loc_ger and rename to ...\loc_eng (not sure if this is necessary or not, but I did it)
5) get a free hex editor (there are many available, I use XVI32)
6) basically check all files within ...\Steel Armor\data\mtc80\ (including subfolders), search for the string "loc_ger" and replace all of them with "loc_eng". This is the most boring part of the process, but actually many files (textures, videos, polygons, icons, and many data files) do not contain the string, so it can be done in 10-15 minutes.
7) apply the core update provided by graviteam
8) apply the march beta patch
9) start the game: it is in English, patched up and everything works (as far as I have seen so far).
Lars