replace anchored image by a character

Here you go. You'll have to create the character style in your document, and I've assumed that it is not inside a CharacterStyleGroup.

//DESCRIPTION: Replace Anchored Images with Styled Text
(function(){
          if (app.documents.length > 0) {
                    var anchArray = [
                              // edit names; add new pairs as needed
                              {'name' : "parking.eps", 'char' : "§"}, 
                              {'name' : "swimmingpool.eps", 'char' : "#"},
                              {'name' : "o-fc1_setup.pdf", 'char' : "∏"} // my test case
                    ]
                    replaceAnchors(app.documents[0], anchArray);
          }
          function replaceAnchors(aDoc, anchArray) {
                    var links = aDoc.links.everyItem().getElements();
                    for (var j = links.length - 1; j >= 0; j--) {
                              var anchor = getAnchor(links);
                              if (anchor == null) continue; // link not anchored
                              var aChar = getCharacter(links.name, anchArray);
                              if (aChar != null) {
                                        anchor.contents = aChar;
                                        anchor.appliedCharacterStyle = "StyleKYB"
                              }
                    }
          }
          function getCharacter(linkName, anchArray) {
                    for (var j = anchArray.length - 1; j >= 0; j--) {
                              if (linkName == anchArray.name) {
                                        return anchArray['char'];
                              }
                    }
                    return null;
          }
          function getAnchor(link) {
                    var theChar = link.parent.parent.parent;
                    if (theChar instanceof Character) {
                              return theChar;
                    }
                    return null; // not anchored
          }
}())
I'd appreciate you indicating that I have correctly answered your question.
Thanks,
Dave