It can be done using the import but there are some extra steps, the standard import won't do it.  
 
1.  Create a text file containing the part number in the first column and the information you want to bring in in the subsequent column(s)
2.  Save in DBAMFG as a comma delimited file
3.  Get all users out of DBA until you are done
4.  Copy the following 3 files for the company you are changing:
BKICMSTR.BXX to BKICEMTR.BXX
BKICLOC.BXX to BKICELOC.BXX
MTICMSTR.BXX to MTICEMTR.BXX
Where XX is the company code (or blank for the default company)
5.  Use DE-B to import the text file, answering R to replace existing part numbers
6.  Use DE-I-A to be sure there are no errors.
7.  Do step 4 in reverse copying the files back.