RPG III, SCAN and replacing sub string

My project: in an existing RPG III program, that must remain RPG III
(bummer) scan in input field from the display file, and replace any slashes
'/' with dashes '-' before storing, because slashes mess up our EDI
transmission.

Relatively easy to find the location of slashes in RPG III, code snippet
follows (do while loop not shown).

C                     MOVE '12/34/56'RESULT  8
C           RESULT    DSPLY
C           '/'       SCAN RESULT    POS     20
C           POS       IFNE *ZERO
C                     ???                      <--- here I need to change
'/' to '-'
C                     ENDIF

How do I, in RPG III, change a character in the middle of a string?  Easy to
do in RPG IV with any number
of BIFs.  But I can't remember how to do this in RPG III.

Any ideas?

Thanks in advance,

Jim Langston