1) The easiest way would be to take the file as a source and use a Derived Column to Find and Replace and then insert them into a new file.. Rename it and delete your old file, If required
2) Use Script Task to open a file, read each column and then do a Replace..
I would go with 1, but it really depends on Number of records in the file ans also believe that Method 1 would be faster.. Not sure though