Jeg har selv fundet et gyldigt svar, og annullerer derfor dette spørgsmål.
Svaret er kopieret fra dette link:
http://windowshelp.microsoft.com/communities/newsgroups/en-us/default.mspx?dg=microsoft.public.windows.vista.general&mid=3ac9ad33-5ed9-4240-9775-24613ca004c7&sloc=en-us
Løsning:
Vista itself has far better multilingual abilities than earlier versions of
Windows. But for compatibility, the NTVDM ("NT Virtual DOS Machine") in
Vista behaves just like the DOS of old ... in other words, it has poor
multilingual abilities! But, you can configure the NTVDM to run a Danish
codepage just like you did on a "real" MS-DOS PC, back in 1992.
First, test that KB16 runs okay, by entering the command:
C:\Windows\System32\KB16 DK,850,C:\Windows\System32\KEYBOARD.SYS
... to enable a Danish keyboard. KB16 should return to a command prompt,
with no messages (error, or otherwise). The Danish keyboard will remain
active until you close the DOS prompt.
On Windows NT (including 2000, XP and Vista) a DOS application takes its
startup environment from the files C:\Windows\System32\Config.NT and
C:\Windows\System32\Autoexec.NT. So to activate a code page for a DOS app,
add the Danish code page commands to C:\Windows\System32\CONFIG.NT and
C:\Windows\System32\AUTOEXEC.NT, the same as you would to C:\CONFIG.SYS and
C:\AUTOEXEC.BAT on a DOS machine.
In CONFIG.NT add to the end of the file:
COUNTRY=045,850,C:\Windows\System32\COUNTRY.SYS
In AUTOEXEC.NT add to the end of the file:
C:\Windows\System32\KB16 DK,850,C:\Windows\System32\KEYBOARD.SYS
Now to test, open a Command Prompt.
Then run the command "command.com". This will start an instance of the
MS-DOS Command processor.
Run the command "edit", to start the DOS editor.
Try typing in a few words in Edit, to see if the new Danish keyboard is in
effect.
If it doesn't work in Edit, then review the above steps carefully.
If it works in Edit, but doesn't work in your old DOS application, then your
app is not taking its code page info from DOS. It may be storing it in a
config file, or the like.
If it works in your application - hey, problem solved!