While this may not be the "best" way, this is how I'd do it. I know looping within a loop is generally slow and to be avoided but it runs fast on my box and I couldn't think of a better/easier way. Just set the ProcessFolder var to the folder with the munged files. The Replace var contains ascii values of the characters to fix.. the second "facet" of the replace array determines what character to replace.. #1 is the ascii value to look for, #2 is what to change it to.
Dim Replace(10, 5)
Set FS = CreateObject("Scripting.FileSystemObject"
ProcessFolder = "c:\swedish"
Replace(1, 1) = 197
Replace(1, 2) = 65
Replace(2, 1) = 196
Replace(2, 2) = 66
Replace(3, 1) = 214
Replace(3, 2) = 67
Set Folder = FS.GetFolder(ProcessFolder)
for each File in Folder.Files
for CurChar = 1 to len(File.Name)
for CurArray = 1 to ubound(Replace)
if asc(mid(File.Name, CurChar, 1)) = Replace(CurArray, 1) then tmpVar = tmpVar & chr(Replace(CurArray, 2)): Replaced = True
next
if Not Replaced then tmpVar = tmpVar & mid(File.Name, CurChar, 1) else Replaced = False
next
FS.MoveFile ProcessFolder & "\" & File.Name, ProcessFolder & "\" & tmpVar
tmpVar = ""
next
wscript.echo "Process Complete!"
Set Folder= Nothing: Set FS = Nothing